Chronologic aging in black skin.

Histologic studies examining chronologic aging in skin have been confined to white skin. In the present study, we examined the features of sun-protected black skin from individuals 6 weeks to 75 years of age with light and electron microscopy. With age, the dermoepidermal junction became flattened with multiple zones of basal lamina and anchoring fibril reduplication. Microfibrils in the papillary dermis became somewhat more irregularly oriented. Compact elastic fibers showed cystic changes and separation of skeleton fibers with age. The area occupied by the superficial vascular plexus in specimens of equal epidermal surface length decreased from the infant to young adult (21-29 years old) to adult (39-52 years old) age groups, then increased in the aged adult (73-75 years old) age group. With the exception of the vascularity in the aged adult group, the above features are similar to those seen in aging white skin, and suggest that chronologic aging in white and black skin is similar. In addition, there was a decrease in the number of melanocytes with age. Basal keratinocyte melanin granule density increased with age to age 52 and remained dense in the aged adult group, even as the number of melanocytes decreased.