optic disc, the small blind spot on the surface of the retina, located about 3 mm to the nasal side of the macula. It is the point where the fibers of the retina leave the eye and become part of the optic nerve.
Adult stem cells are found in many organs and tissues, including the skin. In fact, human skin is the largest repository of adult stem cells in the body. Skin stem cells reside in the basal layer of the epidermis where they remain dormant until they are activated by tissue injury or disease. 1.
1 Melanocyte stem cells are responsible for regeneration of melanocytes, a type of pigment cell. 2  Melanocytes produce the pigment melanin, and therefore play an important role in skin and hair follicle pigmentation. 3  It is not yet certain where these stem cells are found in humans. These stem cells are found in the basal layer of the epidermis. 2  Hair follicle stem cells ensure constant renewal of the hair follicles. 3  They can also regenerate the epidermis and sebaceous glands if these tissues are damaged. 4  Hair follicle stem cells are found throughout the hair follicles.