Histomorphologic changes in aging skin observations in the CBA mouse model

Background: Aging of human skin is a phenomenon resulting from a combination of chronological aging and environmental stressors such as sunlight. Objectives: To study the effects of intrinsic aging on the skin in laboratory-raised CBA mice in 3 age groups, and to assess histological alterations as a function of age in this model. Methods: Skin samples from CBA mice in 3 age groups (young, young adult, and old) were obtained from the dorsal and ventral areas, pinna, and hind foot to study the following variables using light microscopic manual morphometric methods: the depth of the epidermis and number of epidermal cells, depth of the dermis, and percentage area of dermal collagen, elastic fibers, pilosebaceous units, blood vessels, and tissue space. The obtained values were analyzed using 1-way analysis of variance to detect any significant effects of age. Results: There was a notable attrition of the epidermal thickness and number of cells that could be correlated with age. A reduced number of pilosebaceous units was noted in skin samples from the dorsal region and the footpad. No conspicuous change was noted in the depth of the dermis or percentage area of collagen in aging animals. A proliferation of stainable elastic fibers was demonstrated in the dorsal skin and footpad of older mice. Conclusions: CBA mice show unique age-related histological modifications of the skin that are different from other rodent species. These baseline data will be helpful in further studies of regenerative effects of pharmaceutical agents on the histological structure of skin and in photoaging studies.