Histological alterations in liver and testis of Astyanax aff. bimaculatus caused by acute exposition to zinc

Abstract

This study investigated the effect of acute exposition to zinc (Zn) on histology of the liver and testes of yellow
tail lambari (Astyanax aff. bimaculatus). The exposure consisted of six concentrations of Zn (0, 3, 5, 10, 15, and
20 mg/L) for 96 hours of exposure. Fragments of liver and testis were routinely processed and embedded in plastic
resin based on glycol methacrylate. Fragments of bones, muscles, liver and testis were dehydrated and digested to
quantify the absorption levels of Zn in the tissue. Acute exposure to concentrations above 10mg/L has produced
structural changes in the liver and gonads. The changes found in the liver were vascular congestion; decrease of
cellular volume; displacement of the hepatocyte nucleus; necrosis; disarrangement of cordon structure; leukocyte
infiltrate and vacuolization. The changes found in the gonads were ruptured cyst, delayed development of germ
cells, pyknotic nucleus, cell cluster, displacement of cyst wall and vacuolization. The histological changes observed
were compatible with the increasing concentration of zinc in environment, compromising liver and reproductive
functions, because there was an increase in relative frequency of hepatocytes and reduced sperm production.