Gonadal histology of Leptodactylus latrans (Anura, Amphibia) males inhabiting areas impacted by sewage effluents.

MARÍA E. ARRUTI; MARÍA F. BAHL; GABRIELA C. LÓPEZ; GUILLERMO S. NATALE; GUSTAVO M. SOMOZA

Valdivia

Congreso; SETAC Latin America 14th Biennial Meeting; 2021

SETAC Latin America

It is known that different anthropogenic compounds present in sewage effluents affect amphibian reproduction at different levels. It has been demonstrated by our group that some Leptodactylus latrans males inhabiting areas impacted by sewage effluents present secondary sex characteristics resembling those of females. In this context, the aim of this work was to evaluate the if gonadal structure was also affected. Frogs were collected from two sites were these animals normally reproduce in Buenos Aires province (Argentina): Site 1 is characterized by temporal water bodies, used for cattle grazing, with no evident presence of sewage effluents; and Site 2 is clearly affected by sewage effluent downloading in its water bodies. Adult males of this species were collected in both places. Once in the laboratory, everyone was anesthetized, weighed, snout to vent length measured and their gonads were extracted for analysis. Body condition index (relationship between weight and individual volume, snout to vent cubed), and gonadosomatic index (gonadal weight/individual weight x 100) were calculated. Then, testes were fixed, dehydrated, and embedded in paraffin for histological analysis. Each gonad was transversally sectioned at 6 µm and stained with hematoxylin-eosin. Testes cells were classified according to their maturation stage in early stages spermatogenic cells (including primary and secondary spermatogonia, and primary and secondary spermatocytes) and spermatogenic cells at later stages (primary and secondary spermatids and spermatozoa joined to Sertoli cells) and the numbers of cysts with spermatogenic cells at early or late phases were counted. Significance tests (U Mann-Whitney and t test) were made to compare final points between both areas. Of all measured parameters, only snout-vent-length and gonadosomatic index showed differences between places (α=0.05). Individuals from place 2 had a greater snout-vent-length but their gonads were smaller. Our results showed that even if there were morphological differences suggesting that males were affected by the environment, leading to a phenotype ?feminization?, no effects were observed at the gonadal histology. Some more studies are necessary to evaluated if serum androgen level and estradiol/androgens ratio are affected in these males.