ABSTRACT
This chapter reviews the ultrastructure and adaptive value of serous cutaneous glands in pre- and postmetamorphic anurans. Throughout vertebrate phylogenesis, various secretory cell populations have been continuous in the epidermis, characterized by polyphyletic origins, adaptive plasticity, and convergence in their morphological and functional attributes. Both jawless and jawed fishes deploy large complements of mucous and proteinaceous gland cells in their epidermis, involved in functions relevant to the survival strategies in an aquatic habitat. The mucous film on the body surface mediates saline, hydric, and gas exchanges between tissues and environment, and also possesses friction-reducing properties. The proteinaceous secretion varies in composition and role in the different systematic groups, but it is thought to be part of a general defense mechanism against predators, acting as a venom, repellent, or alarm substance. Serous glands in adult anurans sometimes show patterns of biosynthesis, but the metabolic activity of the syncytium merely concerns the final stages of maturation of its product.
