Structural and ultrastructural evaluations of zebrafish ovaries after exposure to 2, 3, 7, 8 - Tetrachlorodibenzo-p-dioxin (TCDD)

Abstract

      The morphological consequences of long-term exposure to low doses of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin in the ovaries were investigated in 50 adult female zebrafish at structural and ultrastructural levels. Animals were exposed to graded concentrations of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (10, 40, 100 and 270 ppb) for 21 days, then zebrafish were sacrificed by an overdose of anaesthetic solution tricaine methanesulfonate, and immediately samples were taken for morphological evaluation. At lower concentrations of exposure there was no evidence of morphological modifications, while at higher concentrations (100 and 270 ppb) we frequently observed degeneration and inflammation. Significant increases in follicular atresia were observed among all groups (p<0.05). These results indicate that long-term exposure to low doses of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin are able to induce morphological damage on the ovaries, which could then produce adverse effects on fish reproductive health.