Ultrastructural studies of elastotic material and elastic fibers in aged skin before and after autoclaving.

Elastotic material and aged elastic fibers of patients with solar elastosis before and after autoclaving was studied using the tannic acid stain as well as the conventional stain. The amorphous matrix of the elastotic material and the elastic fibers stained positive with the tannic acid stain. In the fibrous form of elastotic material and in the elastic fibers both electron-dense inclusions and the amorphous matrix remained unchanged after autoclaving, while microfibrils were removed. In the amorphous form the fine granular component and round bodies were removed after autoclaving, and the moderately electron-dense amorphous component with a reticular or net-like appearance remained. It has been suggested that the elastotic degenerative changes are (1) expansion of the electron-dense inclusions to form a larger part of the fiber; (2) transformation of the inclusions into moderately electron-dense material, composing mainly of a fine granular component and an amorphous one; and (3) disorganization of the moderately electron-dense material.