Phyllomedusa sauvagii lays its eggs surrounded by peculiar vesicles in nests made with tree leaves and, until now, the function of these vesicles was thought to be for maintaining moisture. The histomorphological and histochemical analysis of the oviduct of individuals in ovulatory period, and the study of the vesicles in the oviduct, ovisac and in the nest, showed unexpected results. Vesicles originate from glycoconjugates, proteins and lipids secreted in the PCP and PC and organized in the oviductal lumen and, according to their content, it is possible to recognize at last four types. Furthermore, both in the ovisac and in the nest, vesicles show peculiar relationships with oocites/eggs/embryos through specific communication channels, showing the existence of more complex interactions than previously thought.