An autoradiographic study of the sites of protein synthesis in the epidermis of the Indigo snake (Drymarchon corais couperi)

In order to delineate more clearly the sites of protein synthesis during the synchronous proliferation of reptilian epidermis, H3‐leucine was injected intradermally into the Indigo snake (Drymarchon corais couperi) at various times in the sloughing cycle. Autoradiograms were made of biopsies, taken during the early and late proliferative stages of the molting cycle. These confirmed morphologic observations (Roth and Jones, '66) that moderate numbers of spinous cells are added to the α‐layer during the resting phase. The number of cells added, and the amount of protein synthesized, reaches a maximum in the midresting phase and then decreases. No synthesis of upper α‐layer, μϵσºζ‐layer or β‐layer proteins occurs during the resting phase. Synthesis of the specialized proteins of the β‐layer, the μϵσºζ‐layer and the upper stratum of the α‐layer occurs during the proliferative phase, after the cells have left the basal layer, (while they represent inner epidermal generation), in contrast to mammalian epidermis in which the fibrous proteins are largely synthesized in the basal layer and the lower‐most spinous cells.