MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
Odorous secretions in anurans: morphological and functional assessment 1 of serous glands 2 as a source of volatile compounds in the skin of the treefrog Hypsiboas pulchellus 3 (Amphibia: Anura: Hylidae)
BRUNETTI, A.E.; FAIVOVICH, J.; IURMAN, M. G.; HERMIDA, G.N.
JOURNAL OF ANATOMY
WILEY-BLACKWELL PUBLISHING, INC
Lugar: Londres; Año: 2016 vol. 228 p. 430 - 430
Serous (granular or venom) glands occur in the skin of almost all species of adult amphibians,and are thought to be the source of a great diversity of chemical compounds. Despite recentadvances in their chemistry, odorous volatile substances are the ones that have received less attention, and until now no study has attempted to associate histological data with the presence of these molecules in amphibians, nor in any other vertebrate. Given the recent identification of 40 different volatile compounds from the skin secretions of Hypsiboas pulchellus (a treefrog species that releases a strong odour when handled), we examined the structure, ultrastructure, histochemistry, and distribution of skin glands of this species. Histological analysis from six body regions reveals the presence of two types of glands that differ in their distribution. Mucousglands are homogeneously distributed, whereas serous glands are more numerous in the scapular region. Ultrastructural results indicate that electron translucent vesicles observed within granules of serous glans are similar to those found in volatile-producing glands from insects and also with lipid vesicles from different organisms.Association among lipids and volatiles is also evidenced from chemical results, which indicate that at least some of the volatile components in H. pulchellus probably originate within the metabolism of fatty acids or the mevalonate pathway. Since odorous secretions are often considered to be secreted under stress situations, the release of glandular content was assessed after pharmacological treatments, epinephrine administrated in vivo and on skin explants, and through surface electrical stimulation. Serous glands responded to all treatments, generally through an obvious contraction of myoepithelial cells that surround their secretory portion. No response was observed in mucous glands. Considering these morpho-functional results, along with previous identification of volatiles from H. pulchellus and H. riojanus after electrical stimulation, we suggest that the electron-translucent inclusions found within the granules of serous glands likely are the store sites of volatile compounds and/or theirprecursors. Histochemical and glandular distribution analyses in five other species 50 of frogs of the tribe Cophomantini, revealed a high lipid content in all the species, whereas a heterogeneous distribution of serous glands is only observed in species of the H. pulchellus group. The distribution pattern of serous glands in members of this species group, and the odorous volatile secretions are probably related to defensive functions.