Histopathologic characteristics and ultrastructure of aging skin

Histologic and ultrastructural examination of skin biopsy specimens from younger compared to older persons documents age-related structural alteration in the epidermis, dermal-epidermal junction, dermis, and the epidermal appendages including hair follicles, sebaceous glands, and sweat ducts and glands. The fine, regular epidermal surface patterns change to coarser and less regular ridges with aging. Epidermal projections into the dermis are retracted and the dermal-epidermal junction is flattened. The dermis becomes thinner; there is less fibrous collagen and less elastic fiber in older skin, but the elastic component may appear increased compared to collagen. Elastic fibers may become frayed, porous, and matted together. The density of blood vessels is reduced and, in particular, there are fewer capillary loops in the papillary dermis. There are fewer as well as structurally altered hair follicles, sebaceous glands, and sweat glands with increasing age.