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Abstract

The epidermis of Anolis carolinensis is renewed periodically by molting. Prior to the molt the distinct layers of the epidermis, namely, the Oberhäutchen, beta, mesos, and agr layers, are formed in sequence from a morphologically homogenous population of basal cells. The Oberhäutchen, the first cell layer to form, has spinules on the surface which interdigitate with the overlying cells of the clear layer. The cells of the Oberhäutchen develop 80 Å filaments similar to those in the cells of the agr layer. Beneath the Oberhäutchen is the beta layer, the cells of which develop membrane-bounded packets containing a homogenous material during the early stages of differentiation. Later 100–500 Å thick fibrils are formed in the membranebounded packets. The fully keratinized cells, however, are packed with filaments 30 Å in diameter separated by an electron dense amorphous matrix, very similar to beta-type keratin found in the feather rachis. The cells of the agr layer, which is immediately below the beta layer, contain 80 Å filaments very similar to the agr-type keratin found in hair cortex and keratinizing stratified epithelia of mammals. Large quantities of glycogen are found in the cells of each layer during their genesis. Even though a stratum granulosum is not found underneath the agr layer, the cells of the clear layer develop bodies which have histochemical and ultrastructural characteristics of keratohyalin granules. The old epidermis is then shed in toto at the junction of the clear layer (above) and the Oberhäutchen (below).

Key-Words  Cell differentiation - Keratin - Electron microscopy - Reptiles - Skin

This study constitutes publication No. 406 from the Oregon Regional Primate Research Center, supported in part by postdoctoral training fellowship 1-TIAM-5521-02 and NIH Grant No. FR-00163.

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