where do you find stratified squamous epithelium in the body
upon a basal membrane
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Stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity. Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the surface. In the deeper layers, the cells may be columnar or cuboidal. There are no intercellular spaces. This type of epithelium is well suited to areas
Stratified squamous epithelium
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varying thickness, depending on the age of the epithelium and the damage it has experienced. Keratinized surfaces are protected from abrasion by keratin and kept hydrated and protected from dehydration by glycolipids produced in the stratum granulosum. Examples of keratinized stratified squamous epithelium include epidermis of the palm of the hand and sole of the foot, and the masticatory mucosa. Skin is also covered with stratified squamous epithelium. Stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other
Stratified squamous epithelium
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Stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cells arranged in layers upon a basal membrane. Only one layer is in contact with the basement membrane; the other layers adhere to one another to maintain structural integrity. Although this epithelium is referred to as squamous, many cells within the layers may not be flattened; this is due to the convention of naming epithelia according to the cell type at the surface. In the deeper layers, the cells may be columnar or cuboidal. There are no intercellular spaces. This type of epithelium is well suited to areas
Stratified squamous epithelium
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columnar; (4) pseudostratified. Stratified epithelium differs from simple epithelium in that it is multilayered. It is therefore found where body linings have to withstand mechanical or chemical insult such that layers can be abraded and lost without exposing subepithelial layers. Cells flatten as the layers become more apical, though in their most basal layers the cells can be squamous, cuboidal or columnar. Stratified epithelia (of columnar, cuboidal or squamous type) can have the following specializations: The basic cell types are squamous, cuboidal, and columnar classed by their shape. Cells of epithelial tissue are scutoid shaped, tightly packed and form a
Epithelium
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in the body subject to constant abrasion, as the thickest layers can be sequentially sloughed off and replaced before the basement membrane is exposed. It forms the outermost layer of the skin and the inner lining of the mouth, esophagus and vagina. Non-keratinized surfaces must be kept moist by bodily secretions to prevent them from drying out. Examples of non-keratinized stratified squamous epithelium include corneal epithelium, lining mucosa of oral cavity, esophagus, anal canal, ectocervix, vagina, foreskin, and the internal portion of the lips. Even non-keratinized surfaces, consisting as they do of keratinocytes, have a minor superficial keratinized layer of
Stratified squamous epithelium
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glycogen compared to other epithelial tissue in the body. Under the influence of maternal estrogen, the vagina of a newborn is lined by thick stratified squamous epithelium (or mucosa) for two to four weeks after birth. Between then to puberty, the epithelium remains thin with only a few layers of cuboidal cells without glycogen. The epithelium also has few rugae and is red in color before puberty. When puberty begins, the mucosa thickens and again becomes stratified squamous epithelium with glycogen containing cells, under the influence of the girl's rising estrogen levels. Finally, the epithelium thins out from menopause onward
Vagina
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shape and function of the cells. The three principal shapes associated with epithelial cells are—squamous, cuboidal and columnar. By layer, epithelium is classed as either simple epithelium, only one cell thick (unilayered) or stratified epithelium as stratified squamous epithelium, stratified cuboidal epithelium, and stratified columnar epithelium that are two or more cells thick (multi-layered), and both types of layering can be made up of any of the cell shapes. However, when taller simple columnar epithelial cells are viewed in cross section showing several nuclei appearing at different heights, they can be confused with stratified epithelia. This kind of epithelium is
Epithelium
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from the inferior rectal artery and innervation from the inferior rectal nerves, which branch from the pudendal nerve. The pseudostratified columnar epithelium of the gastrointestinal tract transitions to stratified squamous epithelium at the pectinate line. The stratified squamous epithelium gradually accumulates sebaceous and apocrine glands. During puberty, as testosterone triggers androgenic hair growth on the body, pubic hair begins to appear around the anus. Although initially sparse, it fills out by the end of puberty, if not earlier. However, in some genetic populations androgenic hair is less common. Intra-rectal pressure builds as the rectum fills with feces, pushing the feces
Human anus
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benign (i.e. non-cancerous) change that occurs as a response to change of milieu (physiological metaplasia) or chronic physical or chemical irritation (pathological metaplasia). One example of pathological irritation is cigarette smoke that causes the mucus-secreting ciliated pseudostratified columnar respiratory epithelial cells that line the airways to be replaced by stratified squamous epithelium, or a stone in the bile duct that causes the replacement of the secretory columnar epithelium with stratified squamous epithelium (squamous metaplasia). Metaplasia is an adaptation that replaces one type of epithelium with another that is more likely to be able to withstand the stresses it is faced
Metaplasia
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Epithelium Epithelium () is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous, columnar, and cuboidal. These can be arranged in a single layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified
Epithelium
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To prevent the destruction of the respiratory epithelium in these areas, it changes to stratified squamous epithelium, which is better suited to the constant sloughing and abrasion. The squamous layer of the oropharynx is continuous with the esophagus. Respiratory epithelium Respiratory epithelium is a type of ciliated epithelium found lining most of the respiratory tract, where it serves to moisten and protect the airways. It is not present in the larynx and pharynx. It also functions as a barrier to potential pathogens and foreign particles, preventing infection and tissue injury by the action of mucociliary clearance. The respiratory epithelium lining
Respiratory epithelium
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called endothelial cells. Endothelial cells in direct contact with blood are called vascular endothelial cells, whereas those in direct contact with lymph are known as lymphatic endothelial cells. Epithelium can be arranged in a single layer of cells described as "simple", or more than one layer, described as "stratified". By layer, epithelium is classed as either simple epithelium, only one cell thick (unilayered) or stratified epithelium as stratified squamous epithelium, stratified cuboidal epithelium, and stratified columnar epithelium that are two or more cells thick (multi-layered), and both types of layering can be made up of any of the cell shapes.
Anatomical terms of microanatomy
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rectum are composed of nonkeratinized stratified squamous epithelium. Other surfaces that separate body cavities from the outside environment are lined by simple squamous, columnar, or pseudostratified epithelial cells. Other epithelial cells line the insides of the lungs, the gastrointestinal tract, the reproductive and urinary tracts, and make up the exocrine and endocrine glands. The outer surface of the cornea is covered with fast-growing, easily regenerated epithelial cells. A specialised form of epithelium – endothelium forms the inner lining of blood vessels and the heart, and is known as vascular endothelium, and lining lymphatic vessels as lymphatic endothelium. Another type, mesothelium,
Epithelium
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mucosa consists of two layers, the surface stratified squamous epithelium and the deeper lamina propria. In keratinized oral mucosa, the epithelium consists of four layers: In nonkeratinised epithelium, the two deep layers (basale and spinosum) remain the same but the outer layers are termed the "intermediate" and "superficial" layers. Depending on the region of the mouth, the epithelium may be nonkeratinized or keratinized. Nonkeratinized squamous epithelium covers the soft palate, inner lips, inner cheeks, and the floor of the mouth, and ventral surface of the tongue. Keratinized squamous epithelium is present in the gingiva and hard palate as well as
Oral mucosa
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by stratified squamous epithelium cells. The urethra consists of three coats: muscular, erectile, and mucous, the muscular layer being a continuation of that of the bladder. Between the superior and inferior fascia of the urogenital diaphragm, the female urethra is surrounded by the urethral sphincter. Somatic (conscious) innervation of the external urethral sphincter is supplied by the pudendal nerve. The epithelium of the urethra starts off as transitional cells as it exits the bladder. Further along the urethra there are pseudostratified columnar and stratified columnar epithelia, then stratified squamous cells near the external urethral orifice. There are small mucus-secreting urethral
Urethra
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Squamous metaplasia Squamous metaplasia is a benign non-cancerous change (metaplasia) of surfacing lining cells (epithelium) to a squamous morphology. Common sites for squamous metaplasia include the bladder and cervix. Smokers often exhibit squamous metaplasia in the linings of their airways. These changes don't signify a specific disease, but rather usually represent the body's response to stress or irritation. Vitamin A deficiency or overdose can also lead to squamous metaplasia. In regard to the cervix, squamous metaplasia can sometimes be found in the endocervix, as it is composed of simple columnar epithelium, whereas the ectocervix is composed of stratified squamous non-keratinized
Squamous metaplasia
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Mucous membrane of the soft palate The mucous membrane of the soft palate is thin, and covered with stratified squamous epithelium on both surfaces, except near the pharyngeal ostium of the auditory tube, where it is columnar and ciliated. According to Klein, the mucous membrane on the nasal surface of the soft palate in the fetus is covered throughout by columnar ciliated epithelium, which subsequently becomes squamous; some anatomists state that it is covered with columnar ciliated epithelium, except at its free margin, throughout life. Beneath the mucous membrane on the oral surface of the soft palate is a considerable
Mucous membrane of the soft palate
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However, when taller simple columnar epithelial cells are viewed in cross section showing several nuclei appearing at different heights, they can be confused with stratified epithelia. This kind of epithelium is therefore described as pseudostratified columnar epithelium. Transitional epithelium has cells that can change from squamous to cuboidal, depending on the amount of tension on the epithelium. A mucous membrane or mucosa is a membrane that lines various cavities in the body and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is mostly of
Anatomical terms of microanatomy
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in dorsal and ventral surface. The dorsal surface is a stratified squamous keratinized epithelium which is characterized by numerous mucosal projections called papillae. The lingual papillae covers the dorsal side of the tongue towards the front of the terminal groove . The ventral surface is stratified squamous non-keratinized epithelium which is smooth. The tongue begins to develop in the fourth week of embryogenesis from a median swelling, the "median tongue bud" known as the tuberculum impar, of the first pharyngeal arch. In the fifth week a pair of lateral swellings, the lateral lingual swellings "(distal tongue buds)" one on the
Tongue
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Anal canal is divided into three parts. The zona columnaris is the upper half of the canal and is lined by simple columnar epithelium. The lower half of the anal canal, below the pectinate line, is divided into two zones separated by Hilton's white line. The two parts are the zona hemorrhagica and zona cutanea, lined by stratified squamous non-keratinized and stratified squamous keratinized epithelium, respectively. In humans it is approximately 2.5 to 4 cm long, extending from the anorectal junction to the anus. It is directed downwards and backwards. It is surrounded by inner involuntary and outer voluntary sphincters
Anal canal
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oral cavity. To better understand the challenges for building full-thickness engineered oral mucosa it is important to first understand the structure of normal oral mucosa. Normal oral mucosa consists of two layers, the top stratified squamous epithelial layer and the bottom lamina propria. The epithelial layer consists of four layers: Depending on the region of the mouth the epithelium may be keratinized or non-keratinized. Non-keratinized squamous epithelium covers the soft palate, lips, cheeks and the floor of the mouth. Keratinized squamous epithelium is present in the gingiva and hard palate. Keratinization is the differentiation of keratinocytes in the granular layer
Oral mucosa tissue engineering
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connective tissue in the extracellular matrix secreted by the epithelial cells. There are many different types of epithelium, modified to suit a particular function. In the respiratory tract there is a type of ciliated epithelial lining; in the small intestine there are microvilli on the epithelial lining and in the large intestine there are intestinal villi. Skin consists of an outer layer of keratinized stratified squamous epithelium that covers the exterior of the vertebrate body. Keratinocytes make up to 95% of the cells in the skin. The epithelial cells on the external surface of the body typically secrete an extracellular
Anatomy
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Cervical ectropion Cervical ectropion (or cervical eversion) is a condition in which the cells from the 'inside' of the cervical canal, known as glandular cells (or columnar epithelium), are present on the 'outside' of the vaginal portion of the cervix. The cells on the 'outside' of the cervix are called squamous epithelial cells. Where the two cells meet is called the transformation zone, also known as the stratified squamous epithelium. Although having this condition is not an abnormality, it is indistinguishable from early cervical cancer. It may be found incidentally when a vaginal examination (or pap smear test) is done.
Cervical ectropion
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as large part of the vaginal epithelium are derived from Müllerian duct tissue and that phenotypic differences might be due to other causes. The endocervical mucosa is about thick, lined with a single layer of columnar mucous cells, and contains numerous tubular mucous glands which empty viscous alkaline mucus into the lumen. In contrast, the ectocervix is covered with nonkeratinized stratified squamous epithelium, which resembles the squamous epithelium lining the vaginal. The junction between these two types of epithelia is called the squamocolumnar junction. Underlying both types of epithelium is a tough layer of collagen. The mucosa of the endocervix
Cervix
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amount of adenoid tissue. The palatine glands form a continuous layer on its posterior surface and around the uvula. They are primarily mucus-secreting glands, as opposed to serous or mixed secreting glands. Mucous membrane of the soft palate The mucous membrane of the soft palate is thin, and covered with stratified squamous epithelium on both surfaces, except near the pharyngeal ostium of the auditory tube, where it is columnar and ciliated. According to Klein, the mucous membrane on the nasal surface of the soft palate in the fetus is covered throughout by columnar ciliated epithelium, which subsequently becomes squamous; some
Mucous membrane of the soft palate
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layers of the lamina propria. The body is composed of the thyroarytenoid muscle. This layered structure of tissues is very important for vibration of the true vocal folds. The free edge of the vibratory portion of the vocal fold, the anterior glottis, is covered with stratified squamous epithelium. This epithelium is five to twenty-five cells thick with the most superficial layer consisting of one to three cells that are lost to abrasion of the vocal folds during the closed phase of vibration. The posterior glottis is covered with pseudostratified ciliated epithelium. On the surfaces of the epithelial cells are microridges
Histology of the vocal cords
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is then exposed to the acidic environment of the vagina and, through a process of squamous metaplasia, transforms into stratified squamous epithelium. Cervical ectropion is a normal phenomenon, especially in the ovulatory phase in younger women, during pregnancy, and in women taking the oral contraceptive pill, which increases the total estrogen level in the body. It also may be a congenital problem by persistence of the squamocolumnar junction which is normally present prior to birth. Mucopurulent cervicitis may increase the size of the cervical ectropion. Cervical ectropion can be associated with excessive but non-purulent vaginal discharge due to the increased
Cervical ectropion
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normal phonation, but are often used to produce deep sonorous tones in Tibetan chant and Tuvan throat singing, as well as in musical screaming and the death growl vocal style. Mature human vocal folds are composed of layered structures which are quite different at the histological level. The topmost layer comprises stratified squamous epithelium which is bordered by ciliated pseudostratified epithelium. The inner lining surface of this squamous epithelium is covered by a layer of mucus (acting as a mucociliary clearance), which is composed of two layers: a mucinous layer and serous layer. Both mucus layers provide viscous and watery
Vocal cords
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Keratomalacia Keratomalacia is an eye disorder that results from vitamin A deficiency. Vitamin A is required to maintain specialized epithelia (such as in the cornea and conjunctiva). The precise mechanism is still not known, but vitamin A is necessary for the maintenance of the specialized epithelial surfaces of the body. A lack of vitamin A leads to atrophic changes in the normal mucosal surface, with loss of goblet cells, and replacement of the normal epithelium by an inappropriate keratinized stratified squamous epithelium. In addition, the substantia propria of the cornea breaks down and liquefies, resulting in keratomalacia. The resulting cornea
Keratomalacia
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Junctional epithelium The junctional epithelium (JE) is that epithelium which lies at, and in health also defines, the base of the gingival sulcus. The probing depth of the gingival sulcus is measured by a calibrated periodontal probe. In a healthy-case scenario, the probe is gently inserted, slides by the sulcular epithelium (SE), and is stopped by the epithelial attachment (EA). However, the probing depth of the gingival sulcus may be considerably different from the true histological gingival sulcus depth. The junctional epithelium, a nonkeratinized stratified squamous epithelium, lies immediately apical to the sulcular epithelium, which lines the gingival sulcus from
Junctional epithelium
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Squamous cell papilloma A squamous cell papilloma is a generally benign papilloma that arises from the stratified squamous epithelium of the skin, lip, oral cavity, tongue, pharynx, larynx, esophagus, cervix, vagina or anal canal. Squamous cell papillomas are typically associated with human papillomavirus (HPV) while for others the cause is unknown. Squamous cell papilloma of the mouth or throat is generally diagnosed in people between the ages of 30 and 50, and is normally found on the inside of the cheek, on the tongue, or inside of lips. Oral papillomas are usually painless, and not treated unless they interfere with
Squamous cell papilloma
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Pseudostratified columnar epithelium A pseudostratified epithelium is a type of epithelium that, though comprising only a single layer of cells, has its cell nuclei positioned in a manner suggestive of stratified epithelia. As it rarely occurs as squamous or cuboidal epithelia, it is usually considered synonymous with the term pseudostratified columnar epithelium. The term "pseudostratified" is derived from the appearance of this epithelium in section which conveys the erroneous ("pseudo" means almost or approaching) impression that there is more than one layer of cells, when in fact this is a true simple epithelium since all the cells rest on the
Pseudostratified columnar epithelium
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cannulates to give rise to the navicular fossa. Navicular fossa of male urethra The cavernous portion of the urethra is narrow, and of uniform size in the body of the penis, measuring about 6 mm in diameter; it is dilated behind, within the bulb, and again anteriorly within the glans penis, where it forms the fossa navicularis urethrae. The navicular fossa is the spongy part of the male urethra located at the glans penis portion. It is essentially the part right before the external urethral orifice. It is lined by stratified squamous, non-keratinizing epithelium when viewed histologically. During development, the
Navicular fossa of male urethra
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Navicular fossa of male urethra The cavernous portion of the urethra is narrow, and of uniform size in the body of the penis, measuring about 6 mm in diameter; it is dilated behind, within the bulb, and again anteriorly within the glans penis, where it forms the fossa navicularis urethrae. The navicular fossa is the spongy part of the male urethra located at the glans penis portion. It is essentially the part right before the external urethral orifice. It is lined by stratified squamous, non-keratinizing epithelium when viewed histologically. During development, the glans of the penis is initially solid but
Navicular fossa of male urethra
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which keep the lumen closed in the form of an anteroposterior slit. Behind this lies the anal gland which secretes lymphal discharge and built up fecal matter from the colon lining. In animals, gland expungement can be done routinely every 24 – 36 months to prevent infection and fistula formation. It is differentiated from the rectum by the transition of the internal surface from endodermal to skinlike ectodermal tissue. The anal canal is divided into two unequal sections, upper and lower. A whitish line called Hilton's white line indicates the junction between keratinized stratified squamous epithelium and unkeratinized stratified squamous
Anal canal
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the oesophagus from the lumen outwards consists of mucosa, submucosa (connective tissue), layers of muscle fibers between layers of fibrous tissue, and an outer layer of connective tissue. The mucosa is a stratified squamous epithelium of around three layers of squamous cells, which contrasts to the single layer of columnar cells of the stomach. The transition between these two types of epithelium is visible as a zig-zag line. Most of the muscle is smooth muscle although striated muscle predominates in its upper third. It has two muscular rings or sphincters in its wall, one at the top and one at
Esophagus
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palpebral conjunctival vessels will be supplied by both the ophthalmic artery and the external carotid artery, to varying extents. Sensory innervation of the conjunctiva is divided into four parts: The conjunctiva consists of non-keratinized, both stratified squamous and stratified columnar epithelium, with interspersed goblet cells. The epithelial layer contains blood vessels, fibrous tissue, and lymphatic channels. Accessory lacrimal glands in the conjunctiva constantly produce the aqueous portion of tears. Additional cells present in the conjunctival epithelium include melanocytes, T and B cell lymphocytes. The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears
Conjunctiva
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Conjunctiva The conjunctiva lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, and also stratified columnar epithelium. The conjunctiva is highly vascularised, with many microvessels easily accessible for imaging studies. The conjunctiva is typically divided into three parts: Blood to the bulbar conjunctiva is primarily derived from the ophthalmic artery. The blood supply to the palpebral conjunctiva (the eyelid) is derived from the external carotid artery. However, the circulation of the bulbar conjunctiva and palpebral conjunctiva are linked, so both bulbar conjunctival and
Conjunctiva
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The area may look red because the glandular cells are red. While many women are born with cervical ectropion, it can be caused by a number of reasons, such as: The squamocolumnar junction, where the columnar secretory epithelium of the endocervical canal meets the stratified squamous covering of the ectocervix, is located at the external os before puberty. As estrogen levels rise during puberty, the cervical os opens, exposing the endocervical columnar epithelium onto the ectocervix. This area of columnar cells on the ectocervix forms an area that is red and raw in appearance called an ectropion (cervical erosion). It
Cervical ectropion
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Simple squamous epithelium A simple squamous epithelium is a single layer of flat cells in contact with the basal lamina (one of the two layers of the basement membrane) of the epithelium. This type of epithelium is often permeable and occurs where small molecules need to pass quickly through membranes via filtration or diffusion. Simple squamous epithelia are found in capillaries, alveoli, glomeruli, and other tissues where rapid diffusion is required. Cells are flat with flattened and oblong nuclei. It is also called pavement epithelium due to its tile-like appearance. This epithelium is associated with filtration and diffusion. This tissue
Simple squamous epithelium
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epithelium cells stretch readily in order to accommodate fluctuation of volume of the liquid in an organ. (The distal part of the urethra becomes non-keratinized stratified squamous epithelium in females; the part that lines the bottom of the tissue is called the basement membrane.) Transitional epithelium also functions as a barrier between the lumen, or inside hollow space of the tract that it lines and the bloodstream. To help achieve this, the cells of transitional epithelium are connected by tight junctions, or virtually impenetrable junctions that seal together to the cellular membranes of neighboring cells. This barrier prevents re-absorption of
Transitional epithelium
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is extremely thin, and forms a delicate lining. It offers very little protection. Simple squamous epithelium A simple squamous epithelium is a single layer of flat cells in contact with the basal lamina (one of the two layers of the basement membrane) of the epithelium. This type of epithelium is often permeable and occurs where small molecules need to pass quickly through membranes via filtration or diffusion. Simple squamous epithelia are found in capillaries, alveoli, glomeruli, and other tissues where rapid diffusion is required. Cells are flat with flattened and oblong nuclei. It is also called pavement epithelium due to
Simple squamous epithelium
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trachea. Segments of the duct and cysts that occur high in the neck are lined by stratified squamous epithelium, which is essentially identical to that covering the posterior portion of the tongue in the region of the foramen cecum. The disorders that occur in the lower neck more proximal to the thyroid gland are lined by epithelium resembling the thyroidal acinar epithelium. Characteristically, next to the lining epithelium, there is an intense lymphocytic infiltrate. Superimposed infection may convert these lesions into abscess cavities, and rarely, give rise to cancers. Another disorder is that of thyroid dysgenesis which can result in
Thyroid
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region may be partly responsible for the different symptomatic manifestations of LPR in comparison to GERD. In contrast to the resistant stratified squamous epithelium lining the esophagus, the larynx is lined by ciliated respiratory epithelium, which is more fragile and susceptible to damage. While the epithelium lining the esophagus is capable of withstanding as many as 50 instances of exposure to gastric contents each day, which is the uppermost estimate considered to be within the range of normal physiologic functioning, injury to laryngeal epithelium can occur following exposure to only small amounts of acidic gastric contents. LPR presents with non-specific
Laryngopharyngeal reflux
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covered by stratified squamous epithelium. The false vocal folds are not responsible for sound production, but rather for resonance. The exceptions to this are found in Tibetan Chant and Kargyraa, a style of Tuvan throat singing. Both make use of the false vocal folds to create an undertone. These false vocal folds do not contain muscle, while the true vocal folds do have skeletal muscle. The most important role of the larynx is its protecting function; the prevention of foreign objects from entering the lungs by coughing and other reflexive actions. A cough is initiated by a deep inhalation through
Larynx
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Human hair growth The growth of human hair occurs everywhere on the body except for the soles of the feet, the lips, palms of the hands, some external genital areas, the navel, scar tissue, and, apart from eyelashes, the eyelids. Hair is a stratified squamous keratinized epithelium made of multi-layered flat cells whose rope-like filaments provide structure and strength to the hair shaft. Hair follows a specific growth cycle with three distinct and concurrent phases: anagen, catagen, and telogen. Each phase has specific characteristics that determine the length of the hair. The body has different types of hair, including vellus
Human hair growth
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chimaeras, and lungfish, have no true stomach, so that the esophagus effectively runs from the pharynx directly to the intestine, and is therefore somewhat longer. In many vertebrates, the esophagus is lined by stratified squamous epithelium without glands. In fish, the esophagus is often lined with columnar epithelium, and in amphibians, sharks and rays, the esophageal epithelium is ciliated, helping to wash food along, in addition to the action of muscular peristalsis. In addition, in the bat "Plecotus auritus", fish and some amphibians, glands secreting pepsinogen or hydrochloric acid have been found. The muscle of the esophagus in many mammals
Esophagus
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the lower oesophageal sphincter is generally situated about below the z-line. The human esophagus has a mucous membrane consisting of a tough stratified squamous epithelium without keratin, a smooth lamina propria, and a muscularis mucosae. The epithelium of the esophagus has a relatively rapid turnover, and serves a protective function against the abrasive effects of food. In many animals the epithelium contains a layer of keratin, representing a coarser diet. There are two types of glands, with mucus-secreting esophageal glands being found in the submucosa, and esophageal cardiac glands, similar to cardiac glands of the stomach, located in the lamina
Esophagus
4854110
Lingual tonsils The lingual tonsils are two small mounds of lymphatic tissue located at the back of the base of the tongue, one on either side. They are composed of lymphatic tissue that functions to assist the immune system in the production of antibodies in response to invading pathogenic bacteria or viruses. Lingual tonsils are covered externally by stratified squamous nonkeratinized epithelium. The epithelium invaginates inward to form a single crypt. Beneath the epithelium is a layer of lymphoid nodules containing lymphocytes. These tonsils are surrounded by thin capsule of connective tissue which separates them from adjacent structures. Mucous glands
Lingual tonsils
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layers of the skin. It forms a protective barrier over the body's surface, responsible for keeping water in the body and preventing pathogens from entering, and is a stratified squamous epithelium, composed of proliferating basal and differentiated suprabasal keratinocytes. Keratinocytes are the major cells, constituting 95% of the epidermis, while Merkel cells, melanocytes and Langerhans cells are also present. The epidermis can be further subdivided into the following "strata" or layers (beginning with the outermost layer): Keratinocytes in the stratum basale proliferate through mitosis and the daughter cells move up the strata changing shape and composition as they undergo multiple
Skin
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basal lamina (basement membrane without aid of the microscope) is at the interface between the oral epithelium and lamina propria similar to the epidermis and dermis. Oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth and consists of stratified squamous epithelium termed oral epithelium and an underlying connective tissue termed lamina propria. The oral cavity has sometimes been described as a mirror that reflects the health of the individual. Changes indicative of disease are seen as alterations in the oral mucosa lining the mouth, which can reveal systemic conditions, such as diabetes or vitamin
Oral mucosa
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deciduous teeth in proximity to the follicles of unerupted permanent successors may be a factor for triggering this type of cyst formation. Histologically a normal dental follicle is lined by enamel epithelium, whereas a dentigerous cyst is lined by non-keratinized stratified squamous epithelium. Since the dentigerous cyst develops from follicular epithelium it has more potential for growth, differentiation and degeneration than a radicular cyst. Occasionally the wall of a dentigerous cyst may give rise to a more ominous mucoepidermoid carcinoma. Due to the tendency for dentigerous cysts to expand rapidly, they may cause pathological fractures of jaw bones. On fine
Dentigerous cyst
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continuous sheet. They have almost no intercellular spaces. All epithelia is usually separated from underlying tissues by an extracellular fibrous basement membrane. The lining of the mouth, lung alveoli and kidney tubules are all made of epithelial tissue. The lining of the blood and lymphatic vessels are of a specialised form of epithelium called endothelium. Epithelium lines both the outside (skin) and the inside cavities and lumina of bodies. The outermost layer of human skin is composed of dead stratified squamous, keratinized epithelial cells. Tissues that line the inside of the mouth, the esophagus, the vagina, and part of the
Epithelium
3379609
regression is lost. In females, the paramesonephric ducts give rise to the uterine tubes, uterus, and upper portion of the vagina, while the mesonephric ducts degenerate due to the absence of male androgens. In contrast, the paramesonephric ducts begin to proliferate and differentiate in a cranial-caudal progression to form the aforementioned structures. During this time, the single-layered paramesonephric duct epithelium differentiates into other structures, ranging from the ciliated columnar epithelium in the uterine tube to stratified squamous epithelium in the vagina. The paramesonephric ducts and the mesonephric ducts share a majority of the same mesenchyme due to Hox gene expression.
Paramesonephric duct
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with a keratinized stratified squamous epithelium which is continuous of the oesophagus epithelium. Due to the reflux of stomach juices from the main stomach, minor digestive activity takes place in the forestomach. The main stomach, also referred to as the fundic stomach, secretes mucus, protein digesting enzymes and hydrochloric acid to aid the breakdown of food and lined. The stomach lining is reddish–purple, highly convoluted and sometimes trabeculate epithelium. The pyloric stomach secretes enzymes that digest fat as well as alkaline chemicals to neutralize the stomach acid. It is the combined actions of these different compartments that allow whales to
Digestive system of humpback whales
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2.5 to 3 months after the hair begins to shed. Regrowth may be sparser after treatment. UV levels of either 20 or 50 mJ cm in the UV-B range have been shown to inhibit hair growth, reduce hair melanin and damage hair follicles. Human hair growth The growth of human hair occurs everywhere on the body except for the soles of the feet, the lips, palms of the hands, some external genital areas, the navel, scar tissue, and, apart from eyelashes, the eyelids. Hair is a stratified squamous keratinized epithelium made of multi-layered flat cells whose rope-like filaments provide structure
Human hair growth
7071603
of patients who are chronic mouth-breathers. Sometimes, this disease can be found in conjunction with another denture-related disease, an epulis fissuratum. The appearance of an epulis fissuratum microscopically is an overgrowth of stratified squamous epithelium cells. Depending on the how advanced the condition is, pseudoepitheliomatous hyperplasia may be present. In mild cases, treatment consists of removal of the denture with spontaneous regression of the disease. In advanced cases of inflammatory papillary hyperplasia, surgery may be needed, along with behavioral modification toward proper denture use. Clinical presentation and patient history of denture use. Antifungals to reduce erythema, do nothing (usually lasts
Inflammatory papillary hyperplasia
10560078
70% of cases. Histologically, they are lined by stratified squamous epithelium that lacks a granular cell layer and are filled with compact "wet" keratin. Areas consistent with proliferation can be found in some cysts. In rare cases, this leads to formation of a tumor, known as a proliferating trichilemmal cyst. The tumor is clinically benign, although it may display nuclear atypia, dyskeratotic cells, and mitotic figures. These features can be misleading, and a diagnosis of squamous cell carcinoma may be mistakenly rendered. Surgical excision is required to treat a trichilemmal cyst. The method of treatment varies depending on the physician's
Trichilemmal cyst
13091444
spores known as conidia or hyphal fragments. Once introduced in the subcutaneous tissues, the propagules germinate to establish an invasive mycelium associated with sclerotic cells. This proliferation manifests as a well-defined, chronically progressive, crusted ulceration of the skin known as chromoblastomycosis. Clinically it is often misdiagnosed as squamous cell carcinoma. The disease is characterized by the appearance of spherical, brownish yellow cells with thick, darkly pigmented walls. The presence of the agent is associated with host cell proliferation and enlargement known as hyperplasia localized to the stratified squamous epithelium and the formation of mycotic granulomas. Sclerotic bodies are present both
Fonsecaea pedrosoi
2032133
form is epithelia. Epithelium Epithelium () is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous, columnar, and cuboidal. These can be arranged in a single layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells
Epithelium
1614203
ulcer″, but added this name did not imply agreement with ″Barrett’s description of an esophagus lined with gastric mucous membrane as stomach.” A further association was made with adenocarcinoma in 1975. Barrett's esophagus Barrett's esophagus is a condition in which there is an abnormal (metaplastic) change in the mucosal cells lining the lower portion of the esophagus, from normal stratified squamous epithelium to simple columnar epithelium with interspersed goblet cells, these normally present only in the colon. This change is considered to be a premalignant condition because it is associated with a high incidence of further transition to esophageal adenocarcinoma,
Barrett's esophagus
15018932
Tonsillar crypts The human palatine tonsils (PT) are covered by stratified squamous epithelium that extends into deep and partly branched tonsillar crypts, of which there are about 10 to 30. The crypts greatly increase the contact surface between environmental influences and lymphoid tissue. In an average adult palatine tonsil the estimated epithelial surface area of the crypts is 295 cm, in addition to the 45 cm of epithelium covering the oropharyngeal surface. The crypts extend through the full thickness of the tonsil reaching almost to its hemicapsule. In healthy tonsils the openings of the crypts are fissure-like, and the walls
Tonsillar crypts
1614185
Barrett's esophagus Barrett's esophagus is a condition in which there is an abnormal (metaplastic) change in the mucosal cells lining the lower portion of the esophagus, from normal stratified squamous epithelium to simple columnar epithelium with interspersed goblet cells, these normally present only in the colon. This change is considered to be a premalignant condition because it is associated with a high incidence of further transition to esophageal adenocarcinoma, an often deadly cancer. The main cause of Barrett's esophagus is thought to be an adaptation to chronic acid exposure from reflux esophagitis. Barrett's esophagus is diagnosed by endoscopy: observing the
Barrett's esophagus
9574464
Tibetan chant and Tuvan throat singing, as well as in musical screaming and the death growl singing style used in various forms of metal. Simultaneous voicing with the vocal and vestibular folds is diplophonia. Some voice actors occasionally employ small amounts of this phonation for its dark, growling quality while portraying a "villainous" or antagonistic voice. They are lined with respiratory epithelium, while true vocal cords have stratified squamous epithelium. Vestibular fold The vestibular fold (ventricular fold, superior or false vocal cord) is one of two thick folds of mucous membrane, each enclosing a narrow band of fibrous tissue, the
Vestibular fold
6275517
Oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth and consists of stratified squamous epithelium termed oral epithelium and an underlying connective tissue termed lamina propria. The oral cavity has sometimes been described as a mirror that reflects the health of the individual. Changes indicative of disease are seen as alterations in the oral mucosa lining the mouth, which can reveal systemic conditions, such as diabetes or vitamin deficiency, or the local effects of chronic tobacco or alcohol use. Oral mucosa can be divided into three main categories based on function and histology: Oral
Oral mucosa
2245988
lingual surface and the apical portion of the laryngeal surface (since it is vulnerable to abrasion due to its relation to the digestive tract) are covered by stratified squamous non-keratinized epithelium. However, some parts of the laryngeal surface, which is in relation to the respiratory system, has respiratory epithelium: pseudostratified, ciliated columnar cells and mucus secreting goblet cells. The epiglottis arises from the fourth pharyngeal arch. It can be seen as a distinct structure later than the other cartilage of the pharynx, visible around the fifth month of development. A high-rising epiglottis is a normal anatomical variation, visible during an
Epiglottis
1389539
a sphincter of skeletal muscle, the sphincter of the membranous urethra (external urethral sphincter). The bladder's epithelium is termed transitional epithelium which contains a superficial layer of dome-like cells and multiple layers of stratified cuboidal cells underneath when evacuated. When the bladder is fully distended the superficial cells become squamous (flat) and the stratification of the cuboidal cells is reduced in order to provide lateral stretching. The physiology of micturition and the physiologic basis of its disorders are subjects about which there is much confusion, especially at the supraspinal level. Micturition is fundamentally a spinobulbospinal reflex facilitated and inhibited by
Urination
2174134
of the epidermis. The word epidermis is derived through Latin , itself and . Something related to or part of the epidermis is termed epidermal. The human epidermis is a familiar example of epithelium, particularly a stratified squamous epithelium The epidermis primarily consists of keratinocytes (proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerhans cells, Merkel cells, and inflammatory cells. Epidermal thickenings called Rete ridges (or rete pegs) extend downward between dermal papillae. Blood capillaries are found beneath the epidermis, and are linked to an arteriole and a venule. The epidermis itself has
Epidermis
11316673
basolateral membrane of all simple (especially glandular), pseudo-stratified, and transitional epithelia. In contrast, normal squamous stratified epithelia are negative for EpCAM. The level of expression may differ significantly between the individual tissue types. In the gastrointestinal tract, the gastric epithelium expresses very low levels of EpCAM. Expression levels are substantially higher in small intestine, and in colon EpCAM is probably expressed at the highest levels among all epithelial cell types. EpCAM is frequently upregulated in carcinomas but is not expressed in cancers of non-epithelial origin. In cancer cells, EpCAM is expressed in a dispersed pattern across the cell membrane. However,
Epithelial cell adhesion molecule
3371135
keratinocytes, melanocytes, Langerhans cells, and Merkel cells. Of these, keratinocytes are the major component, constituting roughly 95% of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for a cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum
Skin condition
3495863
The bulbar conjunctival microvasculature is known to dilate in response to several stimuli and external conditions, including allergens (e.g. pollen), temperature, time-of-day, contact-lens wear, and acute mild hypoxia. Bulbar conjunctival vasodilation has also been shown to correlate changes in emotional state. Type II diabetes is associated with an increase in average bulbar conjunctival vessel diameter and capillary loss. Sickle-cell anemia is associated with altered average vessel diameter. Conjunctiva The conjunctiva lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, and also stratified columnar
Conjunctiva
13048098
aspiration. The oropharynx is lined by non-keratinised squamous stratified epithelium. The "HACEK" organisms ("Haemophilus, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, Kingella") are part of the normal oropharyngeal flora, which grow slowly, prefer a carbon dioxide-enriched atmosphere, and share an enhanced capacity to produce endocardial infections, especially in young children. "Fusobacterium" is a pathogen. The laryngopharynx, (Latin: "pars laryngea pharyngis"), also known as hypopharynx, is the caudal part of pharynx; it is the part of the throat that connects to the esophagus. It lies inferior to the epiglottis and extends to the location where this common pathway diverges into the respiratory
Pharynx
1455153
mucosal transition can be seen as an irregular zig-zag line, which is often called the z-line. Histological examination reveals abrupt transition between the stratified squamous epithelium of the esophagus and the simple columnar epithelium of the stomach. Normally, the cardia of the stomach is immediately distal to the z-line and the z-line coincides with the upper limit of the gastric folds of the cardia; however, when the anatomy of the mucosa is distorted in Barrets esophagus the true gastro-eshophageal junction can be identified by the upper limit of the gastric folds rather than the mucosal transition. The functional location of
Esophagus
8795452
Nabothian cyst A nabothian cyst (or nabothian follicle) is a mucus-filled cyst on the surface of the cervix. They are most often caused when stratified squamous epithelium of the ectocervix (toward the vagina) grows over the simple columnar epithelium of the endocervix (toward the uterus). This tissue growth can block the cervical crypts (subdermal pockets usually 2–10 mm in diameter), trapping cervical mucus inside the crypts. Nabothian cysts appear most often as firm bumps on the cervix's surface. A woman may notice the cyst when inserting a diaphragm or cervical cap, or when checking the cervix as part of fertility
Nabothian cyst
8795455
nabothian is not spelled with a capital first letter. Nabothian cyst A nabothian cyst (or nabothian follicle) is a mucus-filled cyst on the surface of the cervix. They are most often caused when stratified squamous epithelium of the ectocervix (toward the vagina) grows over the simple columnar epithelium of the endocervix (toward the uterus). This tissue growth can block the cervical crypts (subdermal pockets usually 2–10 mm in diameter), trapping cervical mucus inside the crypts. Nabothian cysts appear most often as firm bumps on the cervix's surface. A woman may notice the cyst when inserting a diaphragm or cervical cap,
Nabothian cyst
8486655
lined by epithelium. The protective tissues of the oral cavity are continuous with the digestive tract are called mucosa or mucous membranes. The cells of the inner oral cavity are called the buccal mucosa. The oral cavity is lined by a stratified squamous epithelium containing about three layers of cells. They line the oral, nasal, and external auditory meatus, (ear), providing lubrication and protection against pathogens. The lips are also protected by specialized sensory cells called Meissner's corpuscles. Blood circulates from the upper systemic loop originating at the aortic arch, and includes: the brachiocephalic artery, left common carotid artery and
Head and neck anatomy
5336414
(inside of the cheeks) or on the gingiva (gums). The condition resembles Oral lichen planus when biopsied. The diagnosis is made with Immunofluorescence techniques, which shows circulating and tissue-bound autoantibodies (particulate stratified squamous-epithelium-specific antinuclear antibody) to DeltaNp63alpha protein, a normal component of the epithelium. Treatment is with hydroxychloroquine. Terms such as "plasma cell gingivostomatitis", "atypical gingivostomatitis" and "idiopathic gingivostomatitis" are sometimes a synonym for plasma cell gingivitis, or specifically to refer to a severe form of plasma cell gingivitis. Stomatitis Stomatitis is inflammation of the mouth and lips. It refers to any inflammatory process affecting the mucous membranes of the
Stomatitis
8807822
basal lamina. The nucleous of these cells, however, are disposed at different levels, thus creating the illusion of cellular stratification. Not all ciliated cells extend to the luminal surface; such cells are capable of cell division providing replacements for cells lost or damaged. Pseudostratified epithelia function in secretion or absorption. If a specimen looks stratified but has cilia, then it is a pseudostratified ciliated epithelium, since stratified epithelia do not have cilia. They are also found in the internal part of the ear. Pseudostratified columnar epithelium A pseudostratified epithelium is a type of epithelium that, though comprising only a single
Pseudostratified columnar epithelium
2032122
therefore described as pseudostratified columnar epithelium. Transitional epithelium has cells that can change from squamous to cuboidal, depending on the amount of tension on the epithelium. Simple epithelium is a single layer of cells with every cell in direct contact with the basement membrane that separates it from the underlying connective tissue. In general, it is found where absorption and filtration occur. The thinness of the epithelial barrier facilitates these processes. In general, simple epithelial tissues are classified by the shape of their cells. The four major classes of simple epithelium are: (1) simple squamous; (2) simple cuboidal; (3) simple
Epithelium
985050
thin fluid coating within all alveoli. The fluid coating is produced by the body in order to facilitate the transfer of gases between blood and alveolar air. The surfactant is produced by the type II cells which are the most numerous cells in the alveoli, yet do not cover as much surface area as the squamous alveolar cells (a squamous epithelium). Type II cells also repair the endothelium of the alveolus when it becomes damaged. Insufficient surfactant in the alveoli can contribute to atelectasis (collapse of part or all of the lung). Without pulmonary surfactant, atelectasis is a certainty; however,
Pulmonary alveolus
14876264
in ruminants, horses and dogs; absent in the cat and poorly developed in boars. The function of the white serous secretion is not known. The secretory endpieces of these glands are lined with simple columnar epithelium; the main ducts are lined with stratified columnar epithelium. These glands do not occur in carnivores, but are present in some form in horses, ruminants and swine. Seminal fluid, the product of this gland, serves as a vehicle for the transport of spermatozoa. Grossly the prostate gland can be divided into two parts: the body and the disseminate part. Low cuboidal to low columnar
Male accessory gland
4700185
epithelium. Squamous metaplasia may be seen in the context of benign lesions (e.g. atypical polypoid adenomyoma), chronic irritation "or" cancer (e.g. endometrioid endometrial carcinoma) as well as pleomorphic adenoma Squamous metaplasia Squamous metaplasia is a benign non-cancerous change (metaplasia) of surfacing lining cells (epithelium) to a squamous morphology. Common sites for squamous metaplasia include the bladder and cervix. Smokers often exhibit squamous metaplasia in the linings of their airways. These changes don't signify a specific disease, but rather usually represent the body's response to stress or irritation. Vitamin A deficiency or overdose can also lead to squamous metaplasia. In regard
Squamous metaplasia
18436881
skin to the spinal cord lined with stratified squamous epithelium, surrounded by dermal and neurological tissue. The tract may terminate in the deep fascia, or even make contact with neural elements. Congenital dermal sinus may form at any point along the midline of the neuraxis, however, the majority form in the lumbar and lumbosacral region (41% and 35% of cases respectively). Congenital dermal sinus is often diagnosed in infants and children. Early diagnosis is important in congenital dermal sinus, so that treatment can be provided early, to prevent progression of associated complications. There three key hallmarks of congenital dermal sinus:
Congenital dermal sinus
6392267
adamantinomatous type, calcifications are visible on neuroimaging and are helpful in diagnosis. The papillary type rarely calcifies. A vast majority of craniopharyngiomas in children are adamantiomatous whereas both subtypes are common in adults. Mixed type tumors also occur. On macroscopic examination, craniopharyngiomas are cystic or partially cystic with solid areas. On light microscopy, the cysts are seen to be lined by stratified squamous epithelium. Keratin pearls may also be seen. The cysts are usually filled with a yellow, viscous fluid which is rich in cholesterol crystals. Of a long list of possible symptoms, the most common presentations include: headaches, growth
Craniopharyngioma
13048100
air and is lined with a stratified squamous epithelium. It is innervated by the pharyngeal plexus. The vascular supply to the laryngopharynx includes the superior thyroid artery, the lingual artery and the ascending pharyngeal artery. The primary neural supply is from both the vagus and glossopharyngeal nerves. The vagus nerve provides a branch termed "Arnolds Nerve" which also supplies the external auditory canal, thus laryngopharyngeal cancer can result in referred otalgia. This nerve is also responsible for the ear-cough reflex in which stimulation of the ear canal results in a person coughing. Inflammation of the pharynx, or pharyngitis, is the
Pharynx
3311957
of the human mouth, visibly touching the cheekbone below the eye. The inside of the cheek is lined with a mucous membrane (buccal mucosa, part of the oral mucosa). During mastication (chewing), the cheeks and tongue between them serve to keep the food between the teeth. The cheeks are covered externally by hairy skin, and internally by stratified squamous epithelium. This is mostly smooth, but may have caudally directed papillae (e.g., in ruminants). The mucosa is supplied with secretions from the Buccal glands, which are arranged in superior and inferior groups. In carnivores, the superior buccal gland is large and
Cheek
2032120
(layered), either squamous, columnar or cuboidal. In some tissues a layer of columnar cells may appear to be stratified due to the placement of the nuclei, this sort of tissue is called pseudostratified. All glands are made up of epithelial cells. Functions of epithelial cells include secretion, selective absorption, protection, transcellular transport, and sensing. Epithelial layers contain no blood vessels, so they must receive nourishment via diffusion of substances from the underlying connective tissue, through the basement membrane. Cell junctions are well-employed in epithelial tissues. In general, epithelial tissues are classified by the number of their layers and by the
Epithelium
8486650
the atlas near the foramen magnum, a large hole () at the base of the skull. The atlas joins with the occipital condyle above and the axis below. The spinal cord passes through the foramen magnum. The head and neck is covered in skin and its appendages, termed the integumentary system. These include hair, sweat glands, sebaceous glands, and sensory nerves. The skin is made up of three microscopic layers: epidermis, dermis, and hypodermis. The epidermis is composed of stratified squamous epithelium and is divided into the following five sublayers or strata, listed in order from outer to inner: The
Head and neck anatomy
2174136
of the junctions, the actin immunofluorescence appears as a border between cells. The epidermis is composed of 4 or 5 layers, depending on the region of skin being considered. Those layers in descending order are: The Malpighian layer ("stratum malpighi") is both the stratum basale and stratum spinosum. The epidermis is separated from the dermis, its underlying tissue, by a basement membrane. As a stratified squamous epithelium, the epidermis is maintained by cell division within the stratum basale. Differentiating cell delaminate from the basement membrane and are displaced outwards through the epidermal layers, undergoing multiple stages of differentiation until, in
Epidermis
775199
sulcular epithelium is nonkeratinized stratified squamous tissue on the gingiva which touches but is not attached to the tooth. Plaque is a biofilm consisting of large quantities of various bacteria that form on teeth. If not removed regularly, plaque buildup can lead to periodontal problems such as gingivitis. Given time, plaque can mineralize along the gingiva, forming "tartar". The microorganisms that form the biofilm are almost entirely bacteria (mainly streptococcus and anaerobes), with the composition varying by location in the mouth. "Streptococcus mutans" is the most important bacterium associated with dental caries. Certain bacteria in the mouth live off the
Human tooth
701201
primarily made up of adipose tissue. Substantial collagen bundles anchor the dermis to the hypodermis in a way that permits most areas of the skin to move freely over the deeper tissue layers. The epidermis is the top layer of skin made up of epithelial cells. It does not contain blood vessels. Its main functions are protection, absorption of nutrients, and homeostasis. In structure, it consists of a keratinized stratified squamous epithelium ; four types of cells: keratinocytes, melanocytes, Merkel cells, and Langerhans cells. The major cell of the epidermis is the keratinocyte, which produces keratin. Keratin is a fibrous
Integumentary system
665112
of taste and sensation is different for the anterior and posterior part of the tongue because they are derived from different embryological structures (pharyngeal arch 1 and pharyngeal arches 3 and 4, respectively). The upper surface of the tongue is covered in masticatory mucosa a type of oral mucosa which is of keratinized stratified squamous epithelium. Embedded in this are numerous papillae that house the taste buds and their taste receptors. The lingual papillae consist of filiform, fungiform, vallate and foliate papillae. and only the filiform papillae are not associated with any taste buds. The tongue can also divide itself
Tongue
15018935
known as "tonsil stones," have a foul smell and can contribute to bad breath; furthermore, they can obstruct the normal flow of pus from the crypts, and may irritate the throat (people with tonsil stones may complain of the feeling that something is stuck in their throat). Tonsillar crypts The human palatine tonsils (PT) are covered by stratified squamous epithelium that extends into deep and partly branched tonsillar crypts, of which there are about 10 to 30. The crypts greatly increase the contact surface between environmental influences and lymphoid tissue. In an average adult palatine tonsil the estimated epithelial surface
Tonsillar crypts
5422963
of the philtrum are two of the facial characteristics of fetal alcohol syndrome, a lifelong disability caused by the consumption of alcohol during pregnancy. The skin of the lips is stratified squamous epithelium. The mucous membrane is represented by a large area in the sensory cortex, and is therefore highly sensitive. The "Frenulum Labii Inferioris" is the frenulum of the lower lip. The "Frenulum Labii Superioris" is the frenulum of the upper lip. The facial artery is one of the six non-terminal branches of the external carotid artery. This artery supplies both lips by its superior and inferior labial branches.
Lip
7624359
Lacrimal canaliculi The lacrimal canaliculi, (sing. canaliculus), also known as the lacrimal canals or lacrimal ducts, are the small channels in each eyelid that commence at minute orifices, termed puncta lacrimalia, on the summits of the papillae lacrimales, seen on the margins of the lids at the lateral extremity of the lacus lacrimalis. At the angles they are dilated into ampullæ. Able to be seen under a microscope, they are lined by nonkeratinizing stratified squamous epithelium surrounded by fibrous tissue. Outside the latter is a layer of striped muscle, continuous with the lacrimal part of the orbicularis oculi; at the
Lacrimal canaliculi
510295
a newborn human baby will only be able to retain about 30 millilitres. In classical anatomy the human stomach is divided into four sections, beginning at the cardia, each of which has different cells and functions. The cardia is defined as the region following the "z-line" of the gastroesophageal junction, the point at which the epithelium changes from stratified squamous to columnar. Near the cardia is the lower oesophageal sphincter. Recent research has shown that the cardia is not an anatomically distinct region of the stomach but a region of the oesophageal lining damaged by reflux. The lesser curvature of
Stomach
18436882
cutaneous abnormalities, infection, and neurological deficits. Congenital dermal sinus is a tract from the surface layer of the skin, through the deeper tissues into the cranial or spinal cavity. The skin findings of this tract can include: The stratified squamous epithelium of the congenital dermal sinus tract can extend to the spinal fascia of the dura mater or all the way to the spinal cord. Thus, the congenital dermal sinus forms a point of entry for infection, this can allow for the formation of an abscess. Infection can then travel up the spinal cord to result in meningitis, which can
Congenital dermal sinus
18705247
the tip is to allow the toe to conform to the structure it will adhere to. The hexagonal design around the outside of the cells (similar to the crickets) is likely to allow for the mucous to spread evenly over the cell. Smooth adhesive pads are found in arboreal possums, which are marsupials that glide between trees. The possum is also capable of using smooth adhesive pads to climb vertically, making use of large toe pads. The pads consist of an epidermal layer of stratified squamous epithelium with the outer most layer's cells being flattened. The pad has alternating ridges
Arthropod adhesion
9568720
20 blood vessels, 60,000 melanocytes, and more than 1,000 nerve endings. The average human skin cell is about 30 micrometers in diameter, but there are variants. A skin cell usually ranges from 25-40 micrometers (squared), depending on a variety of factors. Skin is composed of three primary layers: the epidermis, the dermis and the hypodermis. Epidermis, "epi" coming from the Greek meaning "over" or "upon", is the outermost layer of the skin. It forms the waterproof, protective wrap over the body's surface which also serves as a barrier to infection and is made up of stratified squamous epithelium with an
Human skin
20571656
integrity changes as the cells move to the upper layers of the epidermis. The vagina itself does not contain mucous glands. Though mucous is not produced by the vaginal epithelium, mucous originates from the cervix. The cervical mucous that is located inside the vagina can be used to assess fertility in ovulating women. The Bartholin's glands and Skene's glands located at the entrance of the vagina do produce mucous. The epithelium of the vagina originates from three different precursors during embryonic and fetal development. These are the vaginal squamous epithelium of the lower vagina, the columnar epithelium of the endocervix,
Vaginal epithelium
11109889
with the intermediate hosts or the infective third stage larva, can lead to transmission to humans. The infection usually occurs when someone drinks contaminated water, or consumes an infected beetle. The buccal mucosa, which is the ideal environment for the parasite, is the mucous membrane of the inside of the cheek. It is non-keratinized stratified squamous epithelium, and is continuous with the mucosae of the soft palate, the undersurface of the tongue and the floor of the mouth. "Gongylonema pulchrum", along with most other "Gongylonema" nematodes, has a broad natural host range. This includes hedgehogs, cattle, dogs, cats, ruminants, rabbits,
Gongylonema pulchrum