the stratum basale layer of the epidermis is responsible for cell division and replacement.
which layer of the epidermis is responsible for cell division and replacement?
the stratum basale
the epidermis is the most superficial layer of skin, a squamous epithelium with several strata: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. nourishment is provided to these layers by diffusion from the dermis, since the epidermis is without direct blood supply. the epidermis contains four cell types: keratinocytes, melanocytes, langerhans cells, and merkel cells. of these, keratinocytes are the major component, constituting roughly 95 percent 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 corneum.
list of skin conditions
stromal cells (in the dermis layer) adjacent to the epidermis (the top layer of the skin) release growth factors that promote cell division. this keeps the epidermis regenerating from the bottom while the top layer of cells on the epidermis are constantly being "sloughed" off the body. additionally, stromal cells play a role in inflammation responses, and controlling the amount of cells accumulating at an inflamed region of tissue. certain types of skin cancers (basal cell carcinomas) cannot spread throughout the body because the cancer cells require nearby stromal cells to continue their division. the loss of these stromal growth factors when the cancer moves throughout the body prevents the cancer from invading other organs.
stromal cell