Relation of Redox and Structural Alterations of Rat Skin in the Function of Chronological Aging

Figure 1

Light and electron microscopy of age-related structural changes in the rat skin. In the young skin, all epidermal cell layers have a normal structure and all cells appeared to be healthy (3 days, 15 days, 1 month, and 3 months old). Aging (6-month-, 12-month-, and 21-month-old skin) increases the epidermal layer thickness and the intercellular space throughout the epidermis along with a decrease in epithelial-dermal junction. In old skin, the basal lamina was partially detached and disrupted from the basal cell layer. Desquamation, through reduction in intercellular lipid contents, was seen in the upper layer of the stratum corneum. Intracytoplasmic vacuolization in the keratinocytes increased with aging. Namely, the keratinocyte mitochondria become light and swollen and concentrated around the nucleus to form an electron-lucent structure—“nuclear halo” (black arrow, 21 m, right insets). The numerous small cytoplasmic vacuoles, located near the nucleus, were observed in the basal keratinocytes gradually becoming a large cytoplasmic vacuole. Degenerative cells with a dark cytoplasm (white arrow, 21 m) were also seen in the basal layer of the epidermis. Semifine sections stained with toluidine blue, magnification: ×100, orig.; transmission electron microscopy, magnification: ×8000, orig.