Effects of environmental pollutants on cultured mouse oocytes and granulosa cells

The drying of the Aral Sea for irrigation, followed by an excessive pesticide exposure, is one of the greatest man-made environmental disaster. High levels of reproductive pathologies have been observed in this region for more than 20 years [1,2]. The responsible include Hexachlorocyclohexanes, as the herbicide Lindane, and Dithiocarbamates, as the fungicide Mancozeb. We demonstrated the toxic effect of Mancozeb on mouse oocytes [3,4] characterized by alterations in spindle morphology, a reduction in the formation of male/female pronuclei and a reduced ability to complete meiotic maturation and fertilization. Lindane altered the formation of the first meiotic spindle and polar body extrusion on mouse oocytes in vitro [5]. This was probably due to gap junction inhibition between oocyte and surrounding granulosa cells (GCs) [6]. To understand the ultrastructural morphological alterations on GCs after pesticide exposure, increasing dose of Lindane and Mancozeb were tested on GCs collected from prepubertal CD1 mice ovaries and matured in vitro [3] and studied by transmission and scanning electron microscopies (TEM and SEM) [7,8]. Results indicated dose-dependent detrimental effects on GCs subjected to Lindane or Mancozed exposure, as per the presence of abundant presence of cell debris, the lost of cell contacts, the decrease of microvilli and cytoplasmic processes. In addition, peripheral aggregation of chromatin under the nuclear membrane, extensive plasma membrane blebbing, abundant GC remnants were also present, but more evident after Lindane exposure. In conclusion, our data showed a different dose-dependent toxicity for Lindane and Mancozeb on GCs, associated to morphological signs of cell death. Since alterations of GCs may be associated to impaired oocyte competence and sterility [9], these results may be of interest in the studies addressed to the preservation of fertility, both in animals and humans.