Detection of a fibrous component in keratohyalin granules of newborn rat epidermis

Keratohyalin granules of frozen newborn rat epidermis were stained histologically and immunohistochemically and studied by light and electron microscopy. They showed a variety of reactivity to eosin, hematoxylin, uranyl acetate and rabbit monospecific antikeratin IgG. We found that good preservation of ultrastructure can be obtained from quickly frozen skin, and filamentous components remain after extraction of tissue substances by 0.14 M NaCl in 0.1 M-Tris-HCl buffer, pH 8.0. Furthermore, filaments in keratohyalin granules became immunologically reactive with rabbit anti-keratin IgG after extraction. Poststain with uranyl acetate further facilitated ultrastructural demonstration of filaments in the granules. These results indicate that filaments are one of the constituents of keratohyalin granules and the staining property changes occur in tonofilaments as they associate with other components to form keratohyalin granules.