ELECTRON-MICROSCOPIC ANALYSIS OF THE REGENERATING SCALES IN LIZARD

Ultrastructural analysis of the regenerating tail epidermis of lizards belonging to the genera Lampropholis and Anolis has shown that the apical blastematic and non scaled superficial epidermis (wound epidermis) is made of thin keratinized cells forming mesos and an a-layers. Lipids and keratin (a, while the presence of the beta type is uncertain) are deposited among and into these superficial cells. In more proximal regions, the interscale epidermis is superficially made of mesos and a-cells and under them spinosus-like cells containing a keratin are seen. Electronpale cells containing keratoialin-like granules form a clear layer and under them a new Oberhautchen and beta-layers differentiate down along the forming outer surface of the regenerating scales. Regenerating scales derive from epidermal infoldings and their outer surface grows at faster rate than the inner surface. The outer surface produces typical epidermal generations toward the centre of the scale. Oberhautchen, beta, mesos, and a layers are produced like in the shedding cycle of the normal epidermis. Autoradiographical observation after 3H-thymidine administration have shown that epidermal cells take about six days to migrate from the basal layer to the keratinized superficial layers (beta, mesos or a). The inner surface and the hinge region doe not produce any beta-keratin layers but are covered by a mesos-layer. In this way the regenerated scales are coated by a mesos layer that prevents water loss. The mesos layer covering the inner surface detaches from the Oberhautchen of the outer surface, allowing the emergence of the regenerated scale. In the keratinized scales of Lampropholis, after 30-40 days of tail regeneration, neither lacunar nor clear layers were seen under the differentiating a-layer of the regenerated outer surface. Therefore, when the wound epidermis is shed, it leaves underneath an incomplete new epidermal outer generation to cover the regenerated tail.