Peptide secretion in the cutaneous glands of South America tree frog Phyllomedusa bicolor: an ultrastructural study

The development of the dermal glands of the arboreal frog Phyllomedusa bico lor was investigated by immunocytochemistry and electron microscopy, The 3 types of glands (mucous, lipid and serous) differed in size and secretory a ctivity. The mucous and serous glands were apparent in the tadpole skin, wh ereas the lipid glands developed later in ontogenesis. The peptide antibiot ics dermaseptins and the D-amino acid-containing peptide opioids dermorphin s and deltorphins are abundant in the skin secretions of Ei bicolor, Althou gh these peptides differ in their structure and activity they are derived f rom precursors that have very similar preproregions. We used an antibody to the common preproregion of preprodermaseptins and preprodeltorphins and im munofluorescence analysis to show that only the serous glands are specifica lly involved in the biosynthesis and secretion of dermaseptins and deltorph ins, Scanning and transmission electron microscopy revealed that the serous glands of P. bicolor have morphological features, especially the secretory granules, which differ from those of the glands in Xenopus laevis skin.