Some bacteria secrete potent, destructive exotoxins that erode the integument, causing cellulitis , a severe, destructive, inflammation of the integument. Strains of Streptococcus bacteria commonly cause cellulitis. Individuals with a compromised immune system, or whose skin pH is altered, are susceptible to fungal infections of the skin. Because the skin is a barrier to pathogenic microbes, loss of skin tissue, such as from thermal or chemical burns or trauma, can lead to invasion of deeper tissues and even the blood by microbes. This is serious, because abscesses, deep tissue destruction, septicemia, and even shock can result.
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.