Some hair follicles have receptors for dihydro-epitestosterone, a male hormone. When the hormone binds to these receptors, the follicle ceases to produce the hair shaft. A balding scalp has the potential for hair growth, but only if such receptors could be blocked. Propecia stimulates such non-functioning hair follicles of a balding male into working again, by blocking the receptors for the male hormone. It is composed of several stratified layers of thin cells, called epithelial cells , as well as melanocytes and Langerhans cells.
Races differ as to the density of melanocytes in their skin.
This layer consists of dead cells containing large amounts of keratin protein. These cells also release lipids into the extracellular space. The stratum corneum helps waterproof the skin and also serves as a physical barrier to microbes. Calluses and corns are areas of skin with a very thickstratum corneum. Langerhans cells of the epidermis are immune system cells involved in the detection of pathogens.