INFLUENCE OF ORGANOCHLORINE PESTICIDES ON DEVELOPMENT OF MOUSE EMBRYOS IN-VITRO

The effect of DDT, methoxychlor (MXC), and gamma-hexachlorocyclohexane (gamma HCH) on preimplantation mouse embryos in culture was evaluated by the proportion of eight-cell stage embryos developing to expanded and hatched blastocysts, A concentration of 29 mu g/mL DDT or gamma HC H led to a complete degeneration of exposed embryos, The addition of 2 9 mu g/mL MXC showed blastocyst formation (72.3%), but fewer than half of the blastocysts were intact and only 4.3% hatched from the zona pe llucida, A concentration of 14.5 mu g/mL DDT led to 57.5% blastocyst f ormation and to 6.8% hatched blastocysts; the same concentration of ga mma HCH and MXC showed 66.7 and 95.9% blastocyst formation and 22.9 an d 498 hatched blastocysts, respectively, The addition of 7.25 mu g/mL led to 85.9% (DDT), 77.6% (gamma HCH), and 81% (MXC) blastocysts in to tal, and to 28.2, 35.5, and 49.4% hatched blastocysts, respectively. C ompared with untreated controls, only the 3.625 mu g/mL concentration for all pesticides showed no significant differences in blastocyst for mation and hatching, These results show different toxicity of these th ree pesticides for the preimplantation mouse embryo in the order MXC < gamma HCH less than or equal to DDT).