Histochemistry of skin glands of Trachycephalus aff. venulosus Laurenti, 1768 (Anura, Hylidae)

The skin of the adult tree frog, Trachycephalus aff. venulosus, was investigated by light microscopy. Histochemistry was carried out using various stain techniques and showed the basic integument morphology of the skin with squamous epithelium in the epidermis and connective tissue in the dermis, subdivided into spongy and compact layers. The integument observed contains two types of gland; the mucous glands and granular glands. The mucous glands are small and located in the upper layer of the stratum spongiosum of the connective tissue and contain neutral and acid sulfated glycoproteins. The granular glands are large and form a syncytial secretory compartment within the acinus, which is surrounded by smooth muscle cells. Histochemical analyses demonstrated the presence of collagen proteins in both types of gland. An unusual finding was the different densities of the granules in the granular glands. The morphological characteristics of the integument in Trachycephalus aff. venulosus was also compared with others species of Anura.