Alterations in Gonads and Liver Tissue in Two Neotropical Anuran Species Commonly Occurring in Rice Fields Crops

Abstract

Amphibians find a suitable habitat in rice agroecosystems, but their viability is affected by the sublethal effects of agrochemicals. Animal condition, external morphology, and liver and male gonad tissue histology were examined on Lysapsus limellum and Rhinella bergi, common species that occurs in rice fields (RF) and reference sites (RS) from Santa Fe and Chaco provinces, Argentina, respectively. Animal condition factor showed no significant differences between environments in either species. Males of both species from RF showed asymmetrical testis size. A higher proportion of cysts with early spermatogenesis cell stages were observed in RF specimens than in RS individuals. The proportion of tubules with free spermatozoa differed between environments for L. limellum. Bidder organ presented vacuoles, atretic follicles, and pigmentary cells in R. bergi from Chaco RF. Liver tissues of both species from RF exhibited sinusoid enlargement, hypervascularization, hepatocyte vacuolization, and dilated blood vessels. R. bergi had a higher number of hepatic melanomacrophages in RF than in RS. The histological biomarker was more sensitive than the morphological one to evaluate chronic pesticide exposure using anuran non-target organs (liver, gonads) and Bidder organ. The potential effect of those alterations on the reproductive performance of anurans that commonly occur in agroecosystems needs further research.