Figure 1.

Schematic representation of the cross section of the skin. The skin is composed of epidermis, dermis, and hypodermis. The dermis supports and provides nourishment to the overlying epidermis through its constituent blood and lymphatic vessels. The skin also comprises sensory elements, various resident cell types like fibroblasts, macrophages, and lymphocytes. The ectodermally derived appendage such as sweat glands, sebaceous glands, and hair follicles arises as an invagination of the epidermis into the dermis. The epidermal stem cells are found in the bulge region of the hair follicles, in the basal layer of the interfollicular epidermis, and to some extent the sebaceous glands.