Morphological alterations in mouse testis by a single dose of malathion

Malathion® is a widely used organophosphorate agropesticide. In spite of its low toxicity for mammalian cells, it provokes cytogenetic and genotoxic damage both in vivo and in vitro. The effect of Malathion was analyzed in CF-1 young adult male mice. Commercial Malathion (96.6% purity) was injected intraperitoneally in a single dose (250 mg/kg body weight corresponding to 1/12 LD50). Four, 14, 18, and 26 days after injection animals were sacrificed to study epididymal sperm (count and morphology), testicular histology (percentage of depleted seminiferous tubules), and ultrastructural alterations in the germinal epithelium. The effect of Malathion on different germinal cell populations was studied. Teratozoospermia was induced by Malathion at all times studied. Spermatozoa midpiece and flagella were the most affected and at day 18 we observed less alterations of the head. The sperm count at different time intervals was significatively increased compared to controls and there was a parallel increase in depletion of the seminiferous tubules. In conclusion, all germinal cell populations studied were affected by Malathion. Malathion has a teratogenic effect on mice spermatid differentiation, which compromises mostly the flagella, perhaps due to an alkylating effect that disturbs the normal assembling of tail structural protein components. Apparently, the pachytene spermatocyte stage may be relatively more resistant to the pesticide. The Sertoli cells were affected by the insecticide and their damage at an ultrastructural level is highly significant. Cytoplasmatic vacuolization probably revealed metabolic alteration of these cells. J. Exp. Zool. 284:355–359, 1999. © 1999 Wiley-Liss, Inc.