Concentration-Related Ultrastructural Alterations in Mouse Oocytes Following In Vitro Lindane Exposure

Lindane, a persistent organochlorine pesticide, exerts toxic effects on the female reproductive system, compromising oocyte quality and maturation. However, the effects of this pesticide on mammalian oocyte morphology and ultrastructure remain unknown. This study investigated the effects of Lindane on mouse oocyte ultrastructure using an in vitro model with Transmission Electron Microscopy (TEM) at concentrations from 1 to 100 μM. The results revealed a progressive dose-related trend of alterations: at 1 μM, mild swelling of smooth endoplasmic reticulum (SER) vesicles; at 10 μM, increased SER dilation and cytoplasmic disorganization; and at 100 μM, pronounced vacuolization, mitochondrial swelling, dense lamellar bodies (dlbs), and multivesicular bodies (MVBs) indicative of autophagic activity. Mitochondrial alterations increased significantly with concentration: 3.2 ± 0.8 (control), 5.7 ± 1.0 (1 μM), 9.4 ± 1.5 (10 μM), and 16.8 ± 2.3 (100 μM) altered mitochondria per oocyte (p < 0.01). Vacuole frequency was notably elevated at 100 μM (4.3 ± 1.1 vs. 0.7 ± 0.5 in controls), and mislocalization of organelles within the ooplasm was observed. In conclusion, Lindane-induced oocyte ultrastructural alterations were observed at all tested concentrations but were more pronounced at 100 μM. These results highlight its impact on female fertility and may guide the search for protective agents, as well as efforts to reduce environmental exposure to endocrine disruptors.