Keratohyalin-like granules in embryonic and regenerating epidermis of lizards and Sphenodon punctatus (Reptilia, Lepidosauria)

Abstract

Epidermal shedding in lepidosaurians is determined by the formation of an intraepidermal shedding complex, made of an upper clear layer which interdigitates with a lower oberhautchen layer. The latter produces species-specific microornamentations. The ultrastucture of embryonic and regenerating epidermis in seven species of lizards representing five different squamate families (Gekkonidae, Agamidae, Lacertidae, Iguanidae and Scincidae), and on the regenerating caudal epidermis of the tuatara (Sphenodon punctatus, suborder Sphenodontia), has shown a broad variation in dimension and morphology of keratohyalin-like granules present in the clear layer of the shedding complex. Where the oberhautchen ornamentations are well developed, like in the setae of the climbing pads, keratohyalin-like granules appear more irregular, larger or more numerous. The present study suggests that keratohyalin-like granules might be involved in the formation of a fibrous network around the forming oberhautchen microornamentations.