where are the male gametes produced in plants
the anther
157515
is produced by the anther, when pollen lands on a mature stigma of a flower it grows a pollen tube down into the flower. The haploid pollen then produces sperm by mitosis and releases them for fertilization. Gamete A gamete (; from Ancient Greek γαμετή "gamete" from gamein "to marry") is a haploid cell that fuses with another haploid cell during fertilization (conception) in organisms that sexually reproduce. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an
Gamete
2088534
In some fungi, such as the Zygomycota, the gametangia are single cells, situated on the ends of hyphae, which act as gametes by fusing into a zygote. More typically, gametangia are multicellular structures that differentiate into male and female organs: In angiosperms, the male gametes (always two) are produced inside the pollen tube (in 70% of the species) or inside the pollen grain (in 30% of the species) through the division of a generative cell into two sperm nuclei. Depending on the species, this can occur while the pollen forms in the anther (pollen tricellular) or after pollination and growth
Gametogenesis
8947427
These microspore mother cells, also called microsporocytes, then undergo meiosis and become four microspore haploid cells. These new microspore cells then undergo mitosis and form a tube cell and a generative cell. The generative cell then undergoes mitosis one more time to form two male gametes, also called sperm. Microgametogenesis Microgametogenesis is the process in plant reproduction where a microgametophyte develops in a pollen grain to the three-celled stage of its development. In flowering plants it occurs with a microspore mother cell inside the anther of the plant. When the microgametophyte is first formed inside the pollen grain four sets
Microgametogenesis
12967454
embryos. Animals typically produce gametes directly by meiosis. Male gametes are called sperm, and female gametes are called eggs or ova. In animals, fertilization follows immediately after meiosis. Plants on the other hand have mitosis occurring in spores, which are produced by meiosis. The spores germinate into the gametophyte phase. The gametophytes of different groups of plants vary in size; angiosperms have as few as three cells in pollen, and mosses and other so called primitive plants may have several million cells. Plants have an alternation of generations where the sporophyte phase is succeeded by the gametophyte phase. The sporophyte
Sexual reproduction
5026095
to move. There is a good argument that this pattern was driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproduction. Accordingly, sex is defined operationally across species by the type of gametes produced (i.e.: spermatozoa vs. ova) and differences between males and females in one lineage are not always predictive of differences in another. Male/female dimorphism between organisms or reproductive organs of different sexes is not limited to animals; male gametes are produced by chytrids, diatoms and land plants, among others. In land plants, "female" and "male" designate not only
Male
364362
Sex Organisms of many species are specialized into male and female varieties, each known as a sex. Sexual reproduction involves the combining and mixing of genetic traits: specialized cells known as gametes combine to form offspring that inherit traits from each parent. The gametes produced by an organism define its sex: males produce small gametes (e.g. spermatozoa, or sperm, in animals; pollen in seed plants) while females produce large gametes (ova, or egg cells). Individual organisms which produce both male and female gametes are termed hermaphroditic. Gametes can be identical in form and function (known as isogamy), but, in many
Sex
364395
daughters as well, who will not be encumbered with such handicaps. Sex Organisms of many species are specialized into male and female varieties, each known as a sex. Sexual reproduction involves the combining and mixing of genetic traits: specialized cells known as gametes combine to form offspring that inherit traits from each parent. The gametes produced by an organism define its sex: males produce small gametes (e.g. spermatozoa, or sperm, in animals; pollen in seed plants) while females produce large gametes (ova, or egg cells). Individual organisms which produce both male and female gametes are termed hermaphroditic. Gametes can be
Sex
5070295
off they develop into new plants. Small pieces of tissue only a few millimetres across are capable of doing this. "C. racemosa" can also reproduce sexually and in so doing exhibits holocarpy. This means that all the organism's cytoplasm is used up in the creation of the gametes and only a husk remains at the site of the original plant. The plants are monoecious with male and female gametes being produced by the same plant and liberated into the water column where they unite to give spherical zygotes. These settle and after five weeks produce germ tubes which elongate and
Caulerpa racemosa
2088533
gametogonia, they are no longer the same between males and females. From gametogonia, male and female gametes develop differently - males by spermatogenesis and females by oogenesis. However, by convention, the following pattern is common for both: In vitro gametogenesis (IVG) is the technique of developing in vitro generated gametes, i.e., "the generation of eggs and sperm from pluripotent stem cells in a culture dish." This technique is currently feasible in mice and will likely have future success in humans and nonhuman primates. Fungi, algae, and primitive plants form specialized haploid structures called gametangia, where gametes are produced through mitosis.
Gametogenesis
49636
several methods used by plants to promote outcrossing. In many land plants the male and female gametes are produced by separate individuals. These species are said to be dioecious when referring to vascular plant sporophytes and dioicous when referring to bryophyte gametophytes. Unlike in higher animals, where parthenogenesis is rare, asexual reproduction may occur in plants by several different mechanisms. The formation of stem tubers in potato is one example. Particularly in arctic or alpine habitats, where opportunities for fertilisation of flowers by animals are rare, plantlets or bulbs, may develop instead of flowers, replacing sexual reproduction with asexual reproduction
Botany
157514
used for human enhancement by selectively breeding for a desired genome or by using recombinant DNA technology to create enhancements that have not arisen in nature. Plants which reproduce sexually also have gametes. However, since plants have an alternation of diploid and haploid generations some differences exist. In flowering plants the flowers use meiosis to produce a haploid generation which produce gametes through mitosis. The female haploid is called the ovule and is produced by the ovary of the flower. When mature the haploid ovule produces the female gamete which are ready for fertilization. The male haploid is pollen and
Gamete
364378
the uterus, an organ which directly supports the development of a fertilized embryo within (a process called gestation). Because of their motility, animal sexual behavior can involve coercive sex. Traumatic insemination, for example, is used by some insect species to inseminate females through a wound in the abdominal cavity—a process detrimental to the female's health. Like animals, plants have developed specialized male and female gametes. Within seed plants, male gametes are contained within hard coats, forming pollen. The female gametes of seed plants are contained within ovules; once fertilized by pollen these form seeds which, like eggs, contain the nutrients
Sex
7568859
the gametes look alike and cannot be classified into "male" or "female." For example, in zygomycetes, two gametangia (single multinucleate cells at the end of hyphae) form good contact with each other and fuse into a zygosporangium. Inside the zygosporangium, the nuclei from each of the original two gametangia pair up. Gametangium A gametangium (plural: gametangia) is an organ or cell in which gametes are produced that is found in many multicellular protists, algae, fungi, and the gametophytes of plants. In contrast to gametogenesis in animals, a gametangium is a haploid structure and formation of gametes does not involve meiosis.
Gametangium
4786132
speaking, the sporophytes of land plants do not have either male or female reproductive organs. The gametophytes of flowering plants are of a single sex; the male gametophytes are contained within the pollen, and the female gametophytes are contained within ovules. The sporophyte generation is called dioecious when each sporophyte has only one kind of spore-producing organ whose spores ultimately give rise to either all male gametes (sperm) or all female gametes (eggs). Slightly different terms, "dioicous" and "monoicous", may be used for the gametophyte generation, although "dioecious" and "monoecious" are also used. Monoecy and dioecy in fungi refer to
Dioecy
9124374
genome. The EsV-1 viral genome is then replicated and virions are assembled in the sporangia or gametangia of infected plants. Viruses are subsequently released via lysis of reproductive cells, stimulated by changes in environmental conditions, such as an increase in temperature. In healthy plants, environmental stimuli synchronize the release of gametes and zoospores into the surrounding water. Free virus particles can then re-infect free-swimming gametes or spores of healthy plants. Infected gametes or spores undergo mitosis, forming infected plants and all cells of the progeny plant contain viral DNA. However, viral particles are only produced in the reproductive cells of
Phycodnaviridae
4643486
Anisogamy Anisogamy (also called heterogamy) is the form of sexual reproduction that involves the union or fusion of two gametes, which differ in size and/or form. (The related adjectives are "anisogamous" and "anisogamic"). The smaller gamete is considered to be male (sperm cell), whereas the larger gamete is regarded as female (egg cell). There are several types of anisogamy. Both gametes may be flagellated and therefore motile. Alternatively, both of the gametes may be non-flagellated. The latter situation occurs in some algae and plants. In the red alga "Polysiphonia", non-motile eggs are fertilized by non-motile sperm. In flowering plants, the
Anisogamy
7568857
Gametangium A gametangium (plural: gametangia) is an organ or cell in which gametes are produced that is found in many multicellular protists, algae, fungi, and the gametophytes of plants. In contrast to gametogenesis in animals, a gametangium is a haploid structure and formation of gametes does not involve meiosis. Depending on the type of gamete produced in a gametangium, several types can be distinguished. Female gametangia are most commonly called archegonia. They produce egg cells and are the sites for fertilization. Archegonia are common in algae and primitive plants as well as gymnosperms. In flowering plants, they are replaced by
Gametangium
9834490
Zoid In botany, a zoid or zoïd is a reproductive cell that possesses one or more flagella, and is capable of independent movement. Zoid can refer to either an asexually reproductive spore or a sexually reproductive gamete. In sexually reproductive gametes, zoids can be either male or female depending on the species. For example, some brown alga ("Phaeophyceae") reproduce by producing multi-flagellated male and female gametes that recombine to form the diploid sporangia. Zoids are primarily found in some protists, diatoms, green alga, brown alga, non-vascular plants, and a few vascular plants (ferns, cycads, and "Ginkgo biloba"). The most common
Zoid
4739797
that isogamy was the first stage of sexual reproduction. In several lineages (plants, animals), this form of reproduction independently evolved to anisogamous species with gametes of male and female types to oogamous species in which the female gamete is very much larger than the male and has no ability to move. There is a good argument that this pattern was driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproduction. In Ascomycetes, anisogamy (sexes) evolved from isogamy before mating types. There are several types of isogamy. Both gametes may be flagellated
Isogamy
8716780
as they become available in future. Cytoplasmic male sterility Cytoplasmic male sterility is total or partial male sterility in plants as the result of specific nuclear and mitochondrial interactions. Male sterility is the failure of plants to produce functional anthers, pollen, or male gametes. Joseph Gottlieb Kölreuter was the first to document male sterility in plants. He reported anther abortion within species and specific hybrids. Cytoplasmic male sterility (CMS) has now been identified in over 150 plant species. Male sterility is more prevalent than female sterility. This could be because the male sporophyte and gametophyte are less protected from the
Cytoplasmic male sterility
8716771
Cytoplasmic male sterility Cytoplasmic male sterility is total or partial male sterility in plants as the result of specific nuclear and mitochondrial interactions. Male sterility is the failure of plants to produce functional anthers, pollen, or male gametes. Joseph Gottlieb Kölreuter was the first to document male sterility in plants. He reported anther abortion within species and specific hybrids. Cytoplasmic male sterility (CMS) has now been identified in over 150 plant species. Male sterility is more prevalent than female sterility. This could be because the male sporophyte and gametophyte are less protected from the environment than the ovule and embryo
Cytoplasmic male sterility
3727631
be identical isospores or come in different sizes (microspores and megaspores), but strictly speaking, spores and sporophytes are neither male nor female because they do not produce gametes. The alternate generation, the gametophyte, produces gametes, eggs and/or sperm. A gametophyte can be monoicous (bisexual), producing both eggs and sperm or dioicous (unisexual), either female (producing eggs) or male (producing sperm). In the bryophytes (liverworts, mosses and hornworts), the sexual gametophyte is the dominant generation. In ferns and seed plants (including cycads, conifers, flowering plants, etc.) the sporophyte is the dominant generation. The obvious visible plant, whether a small herb or
Plant reproductive morphology
18457933
mesenteric lymph nodes (located in the walls of the intestines). Sporulated oocyst then releases 8 sporozoites. These sporozoites attack the intestinal epithelial cells where they develop into a schizont. Schizonts are part of the asexual stages where there are three generations of schizonts. After the last part of the multiplication process, gametes are formed. Gametes are part of the sexual stages, and they can invade other cells. Male gametes divide and break out to the host cell, then go invade cells containing the female gamete. Once the male gametes and the female gamete are in the same host cell, they
Cystoisospora canis
12989607
in new populations. These are the same genes that invade hermaphrodite populations and eventually result in gynodioecy. Gynodioecy is determined as a result of a genetic mutation that stops a plant from producing pollen, but still allows normal female reproductive features. In plants, nuclear genes are inherited from both parents, but all the cytoplasmic genes come from the mother. This holds true in order to compensate for male gametes being smaller and more motile while female gametes are larger. It makes sense for most plants to be hermaphrodites, since they are sessile and unable to find mates as easily as
Gynodioecy
2202339
with flat cristae. When present, paired flagella are used to move the cell. They are anchored by a cross-shaped system of microtubules and fibrous strands. Flagella are only present in the motile male gametes of charophytes bryophytes, pteridophytes, cycads and "Ginkgo", but are absent from the gametes of Pinophyta and flowering plants. Members of the class Chlorophyceae undergo closed mitosis in the most common form of cell division among the green algae, which occurs via a phycoplast. By contrast, charophyte green algae and land plants (embryophytes) undergo open mitosis without centrioles. Instead, a 'raft' of microtubules, the phragmoplast, is formed
Green algae
8584215
function of meiosis.” The gametophyte is the multicellular structure (plant) that is haploid, containing a single set of chromosomes in each cell. The gametophyte produces male or female gametes (or both), by a process of cell division called mitosis. In vascular plants with separate gametophytes, female gametophytes are known as mega gametophytes (mega=large, they produce the large egg cells) and the male gametophytes are called micro gametophytes (micro=small, they produce the small sperm cells). The fusion of male and female gametes (fertilization) produces a diploid zygote, which develops by mitotic cell divisions into a multicellular sporophyte. The mature sporophyte produces
Plant reproduction
364367
evolved alongside the reproduction system, starting with similar gametes (isogamy) and progressing to systems that have different gamete types, such as those involving a large female gamete (ovum) and a small male gamete (sperm). In complex organisms, the sex organs are the parts that are involved in the production and exchange of gametes in sexual reproduction. Many species, both plants and animals, have sexual specialization, and their populations are divided into male and female individuals. Conversely, there are also species in which there is no sexual specialization, and the same individuals both contain masculine and feminine reproductive organs, and they
Sex
94487
Some lineages of eukaryotes, such as land plants, do not have centrioles except in their motile male gametes. Centrioles are completely absent from all cells of conifers and flowering plants, which do not have ciliate or flagellate gametes. It is unclear if the last common ancestor had one or two cilia. Important genes required for centriole growth, like centrins, are only found in eukaryotes and not in bacteria or archaeans. The word "centriole" () uses combining forms of "centri-" and "-ole", yielding "little central part", which describes a centriole's typical location near the center of the cell. Typical centrioles are
Centriole
4643502
of gametes, then this optimum was shown to be one where both small (male) and large (female) gametes are produced. However, these early models assume that natural selection acts mainly at the population level, something that is today known to be a very problematic assumption. The first mathematical model to explain the evolution of anisogamy via individual level selection, and one that became widely accepted was the theory of gamete or sperm competition. Here, selection happens at the individual level: those individuals that produce more (but smaller) gametes also gain a larger proportion of fertilizations simply because they produce a
Anisogamy
3117162
all other land plants, has an alternation of generations; like other bryophytes, the haploid gametophyte generation is dominant and persistent. Unlike other mosses, the long-lived gametophytes do not rely upon rhizoids to assist in water uptake. "Sphagnum" species can be unisexual (male or female, dioecious) or bisexual (male and female gametes produced from the same plant; monoecious); In North America, 80% of "Sphagnum" species are unisexual. Gametophytes have substantial asexual reproduction by fragmentation, producing much of the living material in sphagnum peatlands. Swimming sperm fertilize eggs contained in archegonia that remain attached to the female gametophyte. The sporophyte is relatively
Sphagnum
170435
function of which is to produce haploid spores by meiosis. In some multicellular green algae ("Ulva lactuca" is one example), red algae and brown algae, sporophytes and gametophytes may be externally indistinguishable (isomorphic). In "Ulva" the gametes are isogamous, all of one size, shape and general morphology. In land plants, anisogamy is universal. As in animals, female and male gametes are called, respectively, "eggs" and "sperm." In extant land plants, either the sporophyte or the gametophyte may be reduced (heteromorphic). In bryophytes (mosses, liverworts, and hornworts), the gametophyte is the most visible stage of the life cycle. The bryophyte gametophyte
Gametophyte
548095
Why inheritance ended up being maternal, rather than paternal, is also much debated, but one key hypothesis is that the mutation rate is lower in female compared to male gametes. The conflict between mitochondrial and nuclear genes is especially easy to study in flowering plants. Flowering plants are typically hermaphrodites, and the conflict thus occurs within a single individual. Mitochondrial genes are typically only transmitted through female gametes, and therefore from their point of view the production of pollen leads to an evolutionary dead end. Any mitochondrial mutation that can affect the amount of resources the plant invests in the
Selfish genetic element
533235
(male gametes), pteridophytes (male gametes), some gymnosperms (cycads and "Ginkgo", as male gametes), centric diatoms (male gametes), brown algae (zoospores and gametes), oomycetes (assexual zoospores and gametes), hyphochytrids (zoospores), labyrinthulomycetes (zoospores), some apicomplexans (gametes), some radiolarians (probably gametes), foraminiferans (gametes), plasmodiophoromycetes (zoospores and gametes), myxogastrids (zoospores), metazoans (male gametes), and chytrid fungi (zoospores and gametes). Flagella or cilia are completely absent in some groups, probably due to a loss rather than being a primitive condition. The loss of cilia occurred in red algae, some green algae (Zygnematophyceae), the gymnosperms except cycads and "Ginkgo", angiosperms, pennate diatoms, some apicomplexans, some amoebozoans,
Flagellum
575083
Pollen Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of coniferous plants. If pollen lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require
Pollen
8584219
have distinctive reproductive organs called flowers, with carpels, and the female gametophyte is greatly reduced to a female embryo sac, with as few as eight cells. The male gametophyte consists of the pollen grains. The sperm of seed plants are non-motile, except for two older groups of plants, the Cycadophyta and the Ginkgophyta, which have flagellated sperm. Flowering plants are the dominant plant form on land and they reproduce by sexual and asexual means. Often their most distinguishing feature is their reproductive organs, commonly called flowers. Sexual reproduction in flowering plants involves the production of male and female gametes, the
Plant reproduction
10179154
(hyaline). Pseudothecia are sometimes located alone and other times clustered together. In the asexual stage, conidia, which can also infect plants, are produced in pycnidia. The pycnidia and pseudothecia of "B. dothidea" look very similar. Microconidia have also been reported in at least one "B. dothidea" isolate. Microconidia are small, asexual spores that often act as male gametes or gametangia (spermatia) in a process of cytoplasmic fusion (plasmogamy) According to a key provided in Phillips et al. (2013), "B. dothidea" can be distinguished from six other members of the genus by conidia that are typically longer than 20 μm, have
Botryosphaeria dothidea
575113
also be sprinkled over heads or in mouths. Many Navajo people believe the body becomes holy when it travels over a trail sprinkled with pollen. Pollen Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of coniferous plants. If pollen lands on a compatible pistil or female cone,
Pollen
364383
and female roles. Yeast with the same mating type will not fuse with each other to form diploid cells, only with yeast carrying the other mating type. Many species of higher fungi produce mushrooms as part of their sexual reproduction. Within the mushroom diploid cells are formed, later dividing into haploid spores. The height of the mushroom aids the dispersal of these sexually produced offspring. The most basic sexual system is one in which all organisms are hermaphrodites, producing both male and female gametes— this is true of some animals (e.g. snails) and the majority of flowering plants. In many
Sex
364379
necessary for the development of the embryonic plant. Many plants have flowers and these are the sexual organs of those plants. Flowers are usually hermaphroditic, producing both male and female gametes. The female parts, in the center of a flower, are the pistils, each unit consisting of a carpel, a style and a stigma. One or more of these reproductive units may be merged to form a single compound pistil. Within the carpels are ovules which develop into seeds after fertilization. The male parts of the flower are the stamens: these consist of long filaments arranged between the pistil and
Sex
4623682
ovules are largest in the plant kingdom". Eventough the ovules are largest but seeds are not largest. 1. Cercinate vernation 2. Presence of ramenta 3. Top shaped ciliated male gametes. The plants are dioecious, and the family Cycadaceae is unique among the cycads in not forming seed cones on female plants, but rather a group of leaf-like structures called megasporophylls each with seeds on the lower margins, and pollen cones or strobilus on male individuals. The caudex is cylindrical, surrounded by the persistent petiole bases. Most species form distinct branched or unbranched trunks but in some species the main trunk
Cycas
576701
prokaryotes. The other is that mitosis originated meiosis. The gametes that participate in fertilisation of plants are the pollen (male), and the egg (female) cell. Various families of plants have differing methods by which the female gametophyte is fertilized. In Bryophyte land plants, fertilisation takes place within the archegonium. In flowering plants a second fertilisation event involves another sperm cell and the central cell which is a second female gamete. In flowering plants there are two sperm from each pollen grain.In seed plants, after pollination, a pollen grain germinates, and a pollen tube grows and penetrates the ovule through a
Fertilisation
12252905
Hermaphrodite is used in botany to describe a flower that has both staminate (male, pollen-producing) and carpellate (female, ovule-producing) parts. This condition is seen in many common garden plants. A closer analogy to hermaphroditism in botany is the presence of separate male and female flowers on the same individual—such plants are called monoecious. Monoecy is especially common in conifers, but occurs in only about 7% of angiosperm species. The condition also occurs in some algae. Hermaphrodite In biology, a hermaphrodite () is an organism that has complete or partial reproductive organs and produces gametes normally associated with both male and
Hermaphrodite
8584204
Plant reproduction Reproduction means producing offspring for the survival of the species. Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur. In seed plants, the offspring can be packaged in a protective seed, which is used as an agent of dispersal. Reproduction in which male and
Plant reproduction
864432
Gonad A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes (sex cells) and sex hormones of an organism. In the female of the species the reproductive cells are the egg cells, and in the male the reproductive cells are the sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes, are haploid cells. The gonads are controlled by luteinizing hormone and follicle-stimulating hormone, produced and secreted by gonadotropes or gonadotrophins in the anterior pituitary gland. This secretion is regulated
Gonad
619825
and are produced by meiosis in the sporangium of a diploid sporophyte. Under favourable conditions the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to form a zygote which develops into a new sporophyte. This cycle is known as alternation of generations. The spores of seed plants, however, are produced internally and the megaspores, formed within the ovules and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains. The term "spore" derives
Spore
15572601
wide and sometimes over 30 centimeters long. "Codium fragile" occurs in the low intertidal zone, and subtidal on high-energy beaches. It has no asexual (sporophyte) stage, and male and female gametes are both produced on separate plants. Subspecies of "C. fragile" can only be distinguished microscopically. "Codium fragile" subsp. "atlanticum" is known to have arrived in the southwest of Ireland around 1808. From there it may have spread by rafting or floating in the sea. Approximately 30 years later, it was found in Scotland. It is thought to have originally come from the Pacific Ocean near Japan. Since 1840, when
Codium fragile
10827329
Selfing Selfing or self-fertilization is the union of male and female gametes and/or nuclei from same haploid, diploid, or polyploid organism. It is an extreme degree of inbreeding. Selfing is widespread – from unicellular organisms to the most complex hermaphroditic plants and animals (especially invertebrates). In unicellular organisms such as Protozoa, selfing can occur when two individuals (or their cell nuclei) interbreed that were produced from a previous mitotic division of the same individual. Among hermaphrodite animals there are some that regularly reproduce by self-fertilization. In others, it is a rare event; selfing in such species is more common in
Selfing
725707
defined with respect to a cell. Most eukaryotes have diploid somatic cells, but produce haploid gametes (eggs and sperm) by meiosis. A monoploid has only one set of chromosomes, and the term is usually only applied to cells or organisms that are normally diploid. Male bees and other Hymenoptera, for example, are monoploid. Unlike animals, plants and multicellular algae have life cycles with two alternating multicellular generations. The gametophyte generation is haploid, and produces gametes by mitosis, the sporophyte generation is diploid and produces spores by meiosis. Polyploidy refers to a numerical change in a whole set of chromosomes. Organisms
Polyploidy
4643503
larger number of gametes that 'seek out' those of the larger type. However, because zygotes formed from larger gametes have better survival prospects, this process can again lead to the divergence of gametes sizes into large and small (female and male) gametes. The end result is one where it seems that the numerous, small gametes compete for the large gametes that are tasked with providing maximal resources for the offspring. Some recent theoretical work has challenged the gamete competition theory, by showing that gamete limitation by itself can lead to the divergence of gamete sizes even under selection at the
Anisogamy
19539742
64 zooids, each 5 µm long by 2-3 µm wide. Both gametes are pyriform in shape (pear form) with two laterally inserted flagella (the anterior one longer than the posterior). They each possess one eyespot - and have never been observed to contain two or more. Male and female gametes freely intermingle within a conceptacle, but as long as female gametes are motile, males are not attracted to them. About 4 h after release, female gametes settle on surrounding "Hormosira" tissue, and once that has occurred, the male gametes are then attracted to the settled female gametes. The costs to
Notheia anomala
4317251
testis). Both male and female produce gametes. Male gametocytes are called Spermatocyte and female gametocytes are called Oocytes. The term gametocyte is also used, for example, when talking about gametocytes of species like "Plasmodium falciparum" or "Plasmodium vivax", which transmit malaria. Gametocytes, the precursors of male and female gametes, of malaria parasites are formed in the human host through the developmental switch from asexual replication in erythrocytes. Although gametocytes are not responsible for clinical symptoms, they ensure the transmission of malaria to another host. Upon taking a blood meal, gametocytes are transferred to a mosquito’s midgut lumen where they differentiate
Gametocyte
364375
and female forms—spermatozoa and egg cells. These gametes combine to form embryos which develop into a new organism. The male gamete, a spermatozoon (produced in vertebrates within the testes), is a small cell containing a single long flagellum which propels it. Spermatozoa are extremely reduced cells, lacking many cellular components that would be necessary for embryonic development. They are specialized for motility, seeking out an egg cell and fusing with it in a process called fertilization. Female gametes are egg cells (produced in vertebrates within the ovaries), large immobile cells that contain the nutrients and cellular components necessary for a
Sex
13849762
gamete production takes place in receptacles. The species is monoecious, i.e. an individual is capable of producing male and female gametes. Its cycle of development is monogenic (i.e. only one generation is present during its life cycle). At the level of fertilization: male gametes are dispersed in seawater while female gametes remain in the receptacle where fertilization takes place). Development is also done at the receptacle and then once at the stage of seedling, the latter is detached for fixation on a new support and form a new individual. This species can also reproduce asexually, but this has never been
Sargassum muticum
16007272
to a depth of 24 m or more. It grows from a discoid holdfast with a short stipe. The gametangial plants are dioecious, with male and female gametangia on separate plants. The spermatangia, male gametes, occur in patches near the edges of the fronds. Carposporangia release spores. Tetraspores occur near the margins and consist of four spores. Generally distributed around the British Isles including the Shetland Isles and Isle of Man; from Portugal to Arctic Russia. Dilsea carnosa Dilsea carnosa, commonly known as the poor man's weather glass or the sea belt, is a species of red algae in the
Dilsea carnosa
10350639
of separate species. These may include: Intraspecificity (literally "within species"), or being intraspecific, describes behaviors, biochemical variations and other issues within individuals of a single species. These may include: Two or more individual organisms, populations, or taxa are conspecific if they belong to the same species. Where different species can interbreed and their gametes compete, the conspecific gametes take precedence over heterospecific gametes. This is known as conspecific sperm precedence, or conspecific pollen precedence in plants. The antonym of conspecificity is the term heterospecificity: two individuals are heterospecific if they are considered to belong to different biological species. Congeners are
Biological specificity
2748749
for sexual reproduction. DNA methylation and histone modification have been implicated in the regulation of this process. It starts at puberty and usually continues uninterrupted until death, although a slight decrease can be discerned in the quantity of produced sperm with increase in age (see Male infertility). Spermatogenesis produces mature male gametes, commonly called "sperm" but more specifically known as "spermatozoa", which are able to fertilize the counterpart female gamete, the oocyte, during conception to produce a single-celled individual known as a zygote. This is the cornerstone of sexual reproduction and involves the two gametes both contributing half the normal
Spermatogenesis
364384
cases, however, specialization of sex has evolved such that some organisms produce only male or only female gametes. The biological cause for an organism developing into one sex or the other is called sex determination. In the majority of species with sex specialization, organisms are either male (producing only male gametes) or female (producing only female gametes). Exceptions are common—for example, the roundworm "C. elegans" has an hermaphrodite and a male sex (a system called androdioecy). Sometimes an organism's development is intermediate between male and female, a condition called intersex. Sometimes intersex individuals are called "hermaphrodite"; but, unlike biological hermaphrodites,
Sex
364374
other aspects (anisogamy). By convention, the larger gamete (called an ovum, or egg cell) is considered female, while the smaller gamete (called a spermatozoon, or sperm cell) is considered male. An individual that produces exclusively large gametes is female, and one that produces exclusively small gametes is male. An individual that produces both types of gametes is a hermaphrodite; in some cases hermaphrodites are able to self-fertilize and produce offspring on their own, without a second organism. Most sexually reproducing animals spend their lives as diploid, with the haploid stage reduced to single-cell gametes. The gametes of animals have male
Sex
170436
is longer lived, nutritionally independent, and the sporophytes are typically attached to the gametophytes and dependent on them. When a moss spore germinates it grows to produce a filament of cells (called the protonema). The mature gametophyte of mosses develops into leafy shoots that produce sex organs (gametangia) that produce gametes. Eggs develop in archegonia and sperm in antheridia. In some bryophyte groups such as many liverworts of the order Marchantiales, the gametes are produced on specialized structures called gametophores (or gametangiophores). All vascular plants are sporophyte dominant, and a trend toward smaller and more sporophyte-dependent female gametophytes is evident
Gametophyte
5495256
male gametes (microgametes). This process of formation of flagella-like microgametes or male gametes is known as exflagellation. Macrogametocytes show very little change. They develop a cone of reception at one side and becomes mature as macrogametocytes (female gametes). Male gametes move actively in the stomach of mosquitoes in search of female gametes. Male gametes then enter into female gametes through the cone of reception. The complete fusion of 2 gametes results in the formation of zygote. Here, fusion of 2 dissimilar gametes occurs, known as anisogamy. The zygote remains inactive for sometime but it soon elongates, becomes vermiform (worm-like) and
Plasmodium vivax
94481
Centriole In cell biology a centriole is a cylindrical cellular organelle composed mainly of a protein called tubulin. Centrioles are found in most eukaryotic cells. A bound pair of centrioles, surrounded by a shapeless mass of dense material, called the pericentriolar material (PCM), makes up a structure called a centrosome. Centrioles are present in the cells of most eukaryotes, for example those of animals. However, they are absent from conifers (pinophyta), flowering plants (angiosperms) and most fungi, and are only present in the male gametes of charophytes, bryophytes, seedless vascular plants, cycads, and ginkgo. Centrioles are typically made up of
Centriole
157512
pair as a result of the forementioned reason); ergo the male sperm can play a role in determining the sex of any resulting zygote, if the zygote has two X chromosomes it may develop into a female, if it has an X and a Y chromosome, it may develop into a male. For birds, the female ovum determines the sex of the offspring, through the ZW sex-determination system. Artificial gametes, also known as In vitro derived gametes (IVD), stem cell-derived gametes (SCDGs), and In vitro generated gametes (IVG), are gametes derived from stem cells. Research shows that artificial gametes may
Gamete
576728
fusion of gametes, as in animals and plants. There are three types of fertilisation processes in protozoa: Fertilisation in algae occurs by binary fission. The pseudopodia is first withdrawn and the nucleus starts dividing. When the cytoplasm is divided, the cytoplasm is also divided into two equal parts for each daughter cell. Two daughter cells are produced by one parent cell. It involves the process of mitosis. Fertilisation in fungi. In many fungi (except chytrids), as in some protists, fertilisation is a two step process. ... In chytrid fungi, fertilisation occurs in a single step with the fusion of gametes,
Fertilisation
18342290
some have linear cell arrangement. Parietal chloroplasts have more than two pyrenoids per cell. The distribution is endemic to Indian West Coast. The species is found in intertidal rocks of saline and estuarine environments with various seawater salinities (35 to 24 PSU). The sporangial and gametangial thalli are morphologically alike. The diploid adult plant produces haploid zoospores by meiosis; these settle and grow to form haploid male and female plants similar to the diploid plants. When these haploid plants release gametes they unite to produce the zygote which germinates, and grows to produce the diploid plant. Ulva paschima Ulva paschima
Ulva paschima
170439
sporophyte and a highly reduced megagametophyte develops inside. At maturity, the megaspore cracks open at the trilete suture to allow the male gametes to access the egg cells in the archegonia inside. The gametophytes of "Isoetes" appear to be similar in this respect to those of the extinct Carboniferous giant arborescent clubmosses, "Lepidodendron" and "Lepidostrobus". The seed plants (gymnosperms and angiosperms) are endosporic and heterosporous. The gametophytes develop into multicellular organisms while still enclosed within the spore wall, and the megaspores are retained within the sporangium. In plants with heteromorphic gametophytes, there are two distinct kinds of gametophytes. Because the
Gametophyte
1777577
grows down the style until it reaches an ovary. Sperm cells from the pollen grain then move along the pollen tube, enter an ovum cell through the micropyle and fertilise it, resulting in the production of a seed. A successful angiosperm pollen grain (gametophyte) containing the male gametes is transported to the stigma, where it germinates and its pollen tube grows down the style to the ovary. Its two gametes travel down the tube to where the gametophyte(s) containing the female gametes are held within the carpel. One nucleus fuses with the polar bodies to produce the endosperm tissues, and
Pollination
12582738
into top and bottom sections which then grow into full bodies. In experiments, other species have split successfully, but only when both parts have enough gonadal (reproductive) tissue. All phoronids breed sexually from spring to autumn. Some species are hermaphroditic (have both male and female reproductive organs) but cross-fertilize (fertilize the eggs of other members), while others are dioecious (have separate sexes). The gametes (sperms and ova) are produced in the swollen gonads, around the stomach. The gametes swim through the metacoelom to the metanephridia. Sperm exit by the nephridiopores and some are captured by the lophophores of individuals of
Phoronid
2464488
its roots, stem, leaves and cones or flowers. In flowering plants the gametophytes are very reduced in size, and are represented by the germinated pollen and the embryo sac. The sporophyte produces spores (hence the name) by meiosis, a process also known as "reduction division" that reduces the number of chromosomes in each spore mother cell by half. The resulting meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of chromosomes. The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female
Sporophyte
760600
dependent for its nutrition. In flowering plants, the reduction of the gametophyte is much more extreme; it consists of just a few cells which grow entirely inside the sporophyte. Animals develop differently. They directly produce haploid gametes. No haploid spores capable of dividing are produced, so they do not have a haploid gametophyte alternating with a diploid sporophyte. (Some insects have a sex-determining system whereby haploid males are produced from unfertilized eggs; however the females are diploid.) Life cycles of plants and algae with alternating haploid and diploid multicellular stages are referred to as diplohaplontic (the equivalent terms haplodiplontic, diplobiontic
Alternation of generations
8584218
reproduced by using spores dispersed on the wind. The seed plants including seed ferns, conifers and cordaites, which were all gymnosperms, evolved 350 million years ago; they had pollen grains that contained the male gametes for protection of the sperm during the process of transfer from the male to female parts. It is believed that insects fed on the pollen, and plants thus evolved to use insects to actively carry pollen from one plant to the next. Seed producing plants, which include the angiosperms and the gymnosperms, have heteromorphic alternation of generations with large sporophytes containing much reduced gametophytes. Angiosperms
Plant reproduction
49635
genetic differences between plants and other organisms. Species boundaries in plants may be weaker than in animals, and cross species hybrids are often possible. A familiar example is peppermint, "Mentha" × "piperita", a sterile hybrid between "Mentha aquatica" and spearmint, "Mentha spicata". The many cultivated varieties of wheat are the result of multiple inter- and intra-specific crosses between wild species and their hybrids. Angiosperms with monoecious flowers often have self-incompatibility mechanisms that operate between the pollen and stigma so that the pollen either fails to reach the stigma or fails to germinate and produce male gametes. This is one of
Botany
29929
some protists, who undergo "meiosis" immediately followed by fertilization. Plants and many algae on the other hand undergo "sporic meiosis" where meiosis leads to the formation of haploid spores rather than gametes. These spores grow into multi-cellular individuals (called gametophytes in the case of plants) without a fertilization event. These haploid individuals give rise to gametes through mitosis. Meiosis and gamete formation therefore occur in separate generations or "phases" of the life cycle, referred to as alternation of generations. Since sexual reproduction is often more narrowly defined as the fusion of gametes (fertilization), spore formation in plant sporophytes and algae
Asexual reproduction
11467441
height of around 6 cm, and was free living. It may have been dioicous, i.e. produced male and female gametes on separate plants. "Horneophyton" grew on sandy, organic-rich soil in damp to wet locations. They usually grew as isolated individuals. First named by Kidston & Lang in 1920 from Early Devonian fossils forming the "Rhynie flora", the original generic name "Hornea" transpired to be a synonym, leading to Barghoorn and Darrah renaming the genus to "Horneophyton" in 1938. It was classified as a rhyniophyte (subdivision Rhyniophytina) by Banks; the absence of true vascular tissue led Kenrick and Crane in 1997
Horneophyton
12252894
Hermaphrodite In biology, a hermaphrodite () is an organism that has complete or partial reproductive organs and produces gametes normally associated with both male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the "female" or "male." For example, the great majority of tunicates, pulmonate snails, opisthobranch snails, earthworms and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Most plants are also
Hermaphrodite
533234
and signal transduction. Eukaryotic flagella or cilia, probably an ancestral characteristic, are widespread in almost all groups of eukaryotes, as a relatively perennial condition, or as a flagellated life cycle stage (e.g., zoids, gametes, zoospores, which may be produced continually or not). The first situation is found either in specialized cells of multicellular organisms (e.g., the choanocytes of sponges, or the ciliated epithelia of metazoans), as in ciliates and many eukaryotes with a "flagellate condition" (or "monadoid ", see , an artificial group). Flagellated lifecycle stages are found in many groups, e.g., many green algae (zoospores and male gametes), bryophytes
Flagellum
5062518
dichotomously branched fronds with large, egg-shaped air bladders set in series at regular intervals along the fronds and not stalked. The fronds can reach 2 m in length and are attached by a holdfast to rocks and boulders. The fronds are olive-green, olive-brown in color and somewhat compressed, but without a midrib. Its life history is of one diploid plant and gametes. Each individual plant is either male or female. The gametes are produced in the spring in conceptacles embedded in yellowish receptacles on short branches. Several different varieties and forms of this species have been described. Free-floating forms of
Ascophyllum
8584228
Other plants with similar reproductive means include the "Psilotum", "Lycopodium", "Selaginella" and "Equisetum". The bryophytes, which include liverworts, hornworts and mosses, reproduce both sexually and vegetatively. The gametophyte is the most commonly known phase of the plant. All are small plants found growing in moist locations and like ferns, have motile sperm with flagella and need water to facilitate sexual reproduction. These plants start as a haploid spore that grows into the dominate form, which is a multicellular haploid body with leaf-like structures that photosynthesize. Haploid gametes are produced in antherida and archegonia by mitosis. The sperm released from the
Plant reproduction
15441992
within cells is reset during meiosis (e.g. marks at the FLC locus controlling plant vernalization), though some epigenetic responses have been shown to be conserved (e.g. transposon methylation in plants). Differential inheritance of epigenetic marks due to underlying maternal or paternal biases in removal or retention mechanisms may lead to the assignment of epigenetic causation to some parent of origin effects in animals and plants. In mammals, epigenetic marks are erased during two phases of the life cycle. Firstly just after fertilization and secondly, in the developing primordial germ cells, the precursors to future gametes. During fertilization the male and
Transgenerational epigenetic inheritance
2984669
apex. Antheridium An antheridium is a haploid structure or organ producing and containing male gametes (called "antherozoids" or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. "Androecium" is also used as the collective term for the stamens of flowering plants. Antheridia are present in the gametophyte phase of cryptogams like bryophytes and ferns. Many algae and some fungi, for example ascomycetes and water moulds, also have antheridia during their reproductive stages. In gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains and in most of these the
Antheridium
2984667
Antheridium An antheridium is a haploid structure or organ producing and containing male gametes (called "antherozoids" or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. "Androecium" is also used as the collective term for the stamens of flowering plants. Antheridia are present in the gametophyte phase of cryptogams like bryophytes and ferns. Many algae and some fungi, for example ascomycetes and water moulds, also have antheridia during their reproductive stages. In gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains and in most of these the antheridia
Antheridium
1002055
pollinator community collapsed. Pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insect pollinators include bees, (honey bees, solitary species, bumblebees); pollen wasps (Masarinae); ants; flies including bee flies, hoverflies and mosquitoes; lepidopterans, both butterflies and moths; and flower beetles. Vertebrates, mainly bats and birds, but also some non-bat mammals (monkeys, lemurs, possums, rodents) and some lizards pollinate certain plants. Among the pollinating birds are hummingbirds,
Pollinator
1002034
Pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insect pollinators include bees, (honey bees, solitary species, bumblebees); pollen wasps (Masarinae); ants; flies including bee flies, hoverflies and mosquitoes; lepidopterans, both butterflies and moths; and flower beetles. Vertebrates, mainly bats and birds, but also some non-bat mammals (monkeys, lemurs, possums, rodents) and some lizards pollinate certain plants. Among the pollinating birds are hummingbirds, honeyeaters and sunbirds
Pollinator
8617
and sugars which can account for 50 to 80% of sponge growth in some species. Rhodophyta, Chlorophyta, and Heterokontophyta, the three main algal divisions, have lifecycles which show considerable variation and complexity. In general, an asexual phase exists where the seaweed's cells are diploid, a sexual phase where the cells are haploid, followed by fusion of the male and female gametes. Asexual reproduction permits efficient population increases, but less variation is possible. Commonly, in sexual reproduction of unicellular and colonial algae, two specialized, sexually compatible, haploid gametes make physical contact and fuse to form a zygote. To ensure a successful
Algae
2021725
been shown that if panmictic random fertilization occurred continually, it would maintain the same allele and genotype frequencies across each successive panmictic sexual generation—this being the "Hardy Weinberg" equilibrium. However, as soon as genetic drift was initiated by local random sampling of gametes, the equilibrium would cease. Male and female gametes within the actual fertilizing pool are considered usually to have the same frequencies for their corresponding alleles. (Exceptions have been considered.) This means that when p male gametes carrying the A allele randomly fertilize p female gametes carrying that same allele, the resulting zygote has genotype AA, and, under
Quantitative genetics
12858754
Female Female (♀) is the sex of an organism, or a part of an organism, that produces non-mobile ova (egg cells). Barring rare medical conditions, most female mammals, including female humans, have two X chromosomes. Female characteristics vary between different species with some species containing more well defined female characteristics. Both genetics and environment shape the prenatal development of a female. The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male. A female individual cannot reproduce sexually without access to the gametes of a
Female
9414833
originates a sporophyte composed of a foot, seta, and capsule, where thousands of haploid spores are produced by meiosis. "P. patens" is an excellent model in which to analyze repair of DNA damages in plants by the homologous recombination pathway. Failure to repair double-strand breaks and other DNA damages in somatic cells by homologous recombination can lead to cell dysfunction or death, and when failure occurs during meiosis, it can cause loss of gametes. The genome sequence of "P. patens" has revealed the presence of numerous genes that encode proteins necessary for repair of DNA damages by homologous recombination and
Physcomitrella patens
7265737
Sea coast. "Porphyra" displays a heteromorphic alternation of generations. The thallus we see is the haploid generation; it can reproduce asexually by forming spores which grow to replicate the original thallus. It can also reproduce sexually. Both male and female gametes are formed on the one thallus. The female gametes while still on the thallus are fertilized by the released male gametes, which are non-motile. The fertilized, now diploid, carposporangia after mitosis produce spores (carpospores) which settle, then bore into shells, germinate and form a filamentous stage. This stage was originally thought to be a different species of alga, and
Porphyra
19727522
compared to similar asexual populations. The IR model for the development of anisogamy is named after its developers Priya Iyer and Joan Roughgarden. By considering the evolution of anisogamy in hermaphroditic marine invertebrates and bisexual plants, the theory postulates of a gene locus which controls both sperm and egg size produced by an organism. Anisogamy could evolve in diploid hermaphroditic adults as an individual adaptation which increases its own fitness. Hermaphroditic animals and dioecious plants represent a large portion of sexually reproductive species. Under social selection theory, species where individuals produce two different gametes predate strictly gonochoristic and monoecious species.
Social selection
19881506
released by conidia. Male choice can occur in populations where there is a low concentration of male gametes, allowing them to be selective in which female to fertilize. The female with the highest concentration of pheromone is usually chosen. In situations where fertilization may have to occur over long distances, water-soluble pheromones may be secreted as seen in the female gametes of an aquatic Chytridiomycetes. The same similarly occurs within an aquatic oomycete algae species; also, a variation in the pheromone production related to the male reaction has been observed. Variations within the pheromone production as well as the response
Sexual selection in fungi
5371587
varying by author. The most common rules followed are Omegaverse, which was first established in fanfiction. Male pregnancy Male pregnancy is the incubation of one or more embryos or fetuses by male members of some species. Most species that reproduce by sexual reproduction are heterogamous—females producing larger gametes (ova) and males producing smaller gametes (sperm). In nearly all animal species, offspring are carried by the female until birth, but in fish of the Syngnathidae family (pipefish, seahorses and the leafy seadragon), males perform this function. Human males incubating fetuses are a subject of popular imagination and a recurring theme in
Male pregnancy
401287
The seed plants, which include conifers and flowering plants have small gametophytes that develop inside the pollen grains (male) and the ovule (female). Sexual reproduction in flowering plants involves the union of the male and female germ cells, sperm and egg cells respectively. Pollen is produced in stamens, and is carried to the pistil, which has the ovary at its base where fertilization can take place. Within each pollen grain is a male gametophyte which consists of only three cells. In most flowering plants the female gametophyte within the ovule consists of only seven cells. Thus there are no sex
Sex organ
19881505
equivalent of male-male competition in plants and animals. They may also be choosy when being fertilized, the equivalent to female choice. Sexual selection in fungi aids in explaining certain characteristics including the high redundancy of pheromones in the B mating-type locus as well as strong pheromone signaling in yeasts. Pheromone signaling is used within fungi to either attract a mate or to assess the quality of that gamete; and tends to be more effective when occurring over small distances. Female gametes are typically the ones responsibly for producing pheromones in order to attract a mate. However, pheromones can also be
Sexual selection in fungi
7068770
Oogamy Oogamy is the familiar form of sexual reproduction. It is a form of anisogamy (heterogamy) in which the female gamete (e.g. egg cell) is significantly larger than the male gamete and is non-motile. The male gametes are typically highly motile and are usually tasked with all of the travel necessary to bring the respective gametes together. The prevalence of oogamy in higher animals leads to the conclusion that this specialization of the gametes results in their performing their respective tasks better and more efficiently than those tasks could be performed by generalist isogametes, particularly the ability to concentrate high-energy
Oogamy
3727642
complexity of the morphology of flowers and its variation within populations has led to a rich terminology. Outcrossing, cross-fertilization or allogamy, in which offspring are formed by the fusion of the gametes of two different plants, is the most common mode of reproduction among higher plants. About 55% of higher plant species reproduce in this way. An additional 7% are partially cross-fertilizing and partially self-fertilizing (autogamy). About 15% produce gametes but are principally self-fertilizing with significant out-crossing lacking. Only about 8% of higher plant species reproduce exclusively by non-sexual means. These include plants that reproduce vegetatively by runners or bulbils,
Plant reproductive morphology
12552880
sunset time, and possibly chemical signalling. Synchronous spawning may form hybrids and is perhaps involved in coral speciation. In some places the spawn can be visually dramatic, clouding the usually clear water with gametes, typically at night. Corals use two methods for sexual reproduction, which differ in whether the female gametes are released: Fungi are not plants, and require different conditions for optimal growth. Plants develop through photosynthesis, a process that converts atmospheric carbon dioxide into carbohydrates, especially cellulose. While sunlight provides an energy source for plants, mushrooms derive all of their energy and growth materials from their growth medium,
Spawn (biology)
5371564
Male pregnancy Male pregnancy is the incubation of one or more embryos or fetuses by male members of some species. Most species that reproduce by sexual reproduction are heterogamous—females producing larger gametes (ova) and males producing smaller gametes (sperm). In nearly all animal species, offspring are carried by the female until birth, but in fish of the Syngnathidae family (pipefish, seahorses and the leafy seadragon), males perform this function. Human males incubating fetuses are a subject of popular imagination and a recurring theme in speculative fiction. In some very rare genetic conditions, genotypical males develop as female and possess the
Male pregnancy
364373
mixed chromosomes. Crossing over and fertilization (the recombining of single sets of chromosomes to make a new diploid) result in the new organism containing a different set of genetic traits from either parent. In many organisms, the haploid stage has been reduced to just gametes specialized to recombine and form a new diploid organism; in others, such as cryptogamic plants the gametes are capable of undergoing cell division to produce multicellular haploid organisms. In either case, gametes may be externally similar, particularly in size (isogamy), or may have evolved an asymmetry such that the gametes are different in size and
Sex
12967459
means include the "Psilotum", "Lycopodium", "Selaginella" and "Equisetum". The bryophytes, which include liverworts, hornworts and mosses, reproduce both sexually and vegetatively. They are small plants found growing in moist locations and like ferns, have motile sperm with flagella and need water to facilitate sexual reproduction. These plants start as a haploid spore that grows into the dominate form, which is a multicellular haploid body with leaf-like structures that photosynthesize. Haploid gametes are produced in antherida and archegonia by mitosis. The sperm released from the antherida respond to chemicals released by ripe archegonia and swim to them in a film of
Sexual reproduction
10919773
Conceptacle Conceptacles are specialised cavities of marine and freshwater algae that contain the reproductive organs. They are situated in the receptacle and open by a small ostiole. Conceptacles are present in Corallinaceae, and Hildenbrandiales, as well as the brown Fucales. In the Fucales there is no haploid phase in the reproductive cycle and therefore no alternation of generations. The thallus is a sporophyte. The diploid plants produce male (antheridia) and female (oogonia) gametangia by meiosis. The gametes are released into the surrounding water; after fusion, the zygote settles and begins growth. Two taxa, the corallines and Hildenbrandiaceae, bear conceptacles, although
Conceptacle
5735248
oogonia and antheridia form and produce haploid gametes. The only diploid part of the life cycle is the spore (fertilized egg cell), which undergoes meiosis to form haploid cells that develop into new plants. This is a haplontic life cycle (with zygotic meiosis). The oogonia of certain Thallophyte species are usually round or ovoid, with contents are divided into several uninucleate oospheres. This is in contrast to the male antheridia which are elongate and contain several nuclei. In heterothallic species, the oogonia and antheridia are located on hyphal branches of different thallophyte colonies. Oogonia of this species can only be
Oogonium
5142869
reproductive system and forms the Fallopian tubes, uterus, and vagina in the female system. In both sexes the gonads go on to form the testes and ovaries; because they are derived from the same undeveloped structure, they are considered homologous organs. There are a number of other homologous structures shared between male and female reproductive systems. However, despite the similarity in function of the female Fallopian tubes and the male epididymis and vas deferens, they are not homologous but rather analogous structures as they arise from different fetal structures. Gametes are produced within the gonads through a process known as
Human reproductive system