THE STRUCTURE OF THE SKIN OF THE TREE FROG (HYLA-ARBOREA-ARBOREA L.)

The aim of the study was to investigate the structure of the skin of t he adult tree frog Hyla arborea arborea L. by scanning electron micros copy (SEM) and light microscopy (LM). SEM observation shows that the s kin from the dorsal part of body is smooth whereas the ventral part ha s regular ridges and grooves. The superficial layer of the skin consis ts of irregular shaped epidermal cells covered with microridges differ ing on the dorsal and ventral skin. Two types of gland outlets, funnel -type and collar-type, are seen on the surface of the epithelium. The dorsal and ventral skin observed in LM contained three kinds of glands : mucous glands, and two different types of serous glands, type I and II. The mucous glands are small and located in the upper layer of the stratum spongiosum of the connective tissue. The serous glands are lar ge. Type I glands with small secretory granules (1-3 mu m) appear spor adically in both the dorsal and ventral skin. Type II glands with larg e secretory granules (5-15 mu m) are very numerous, particularly in th e dorsal skin. Many capillaries invaginate to the epidermis of the ven tral skin facilitating absorption of water in these sites. The lipid g lands occurring in the skin of phyllomedusine frogs are not observed i n the skin of the tree frog.