An ultrastructural study of ultraviolet-induced elastic fiber damage in hairless mouse skin

Ultrastructural visualization of mouse elastic fibers has been hampered by the small size and sparseness of the fibers. Furthermore, with conventional uranyl acetate and lead citrate stains, the elastin matrix remains electron-lucent so that even severe elastosis is elusive. The addition of tannic acid to the staining procedure renders the elastin matrix extremely electron dense and easily located even at low scanning power. Microfibrils, as with conventional stains, are electron-dense and clearly visible. This study describes, with the aid of tannic acid, normal hairless mouse elastic fibers and their progressive degeneration with increasing exposure to ultraviolet radiation. Results with the two staining methods are contrasted. In addition, photodamaged mouse and human elastic fibers are compared for differences and similarities.