EFFECTS OF IMPAIRED MATERNAL INSULIN-SECRETION ON PREIMPLANTATION EMBRYO DEVELOPMENT IN ICR MICE

To investigate the significance of impaired insulin secretion on preim plantation embryo development, outbred ICR female mice received an inj ection of a single dose of streptozotocin 200 mg.kg(-1) 14-17 days bef ore fertilization. Oocytes were collected 24-26 h after BCG injection. Morphological evaluation revealed a lower percentage of oocytes with second polar bodies from streptozotocin-treated females in comparison with controls Furthermore, in this group the incidence of degenerated embryos significantly increased after 120 h in vitro cultivation. Insu lin (5 U per 100 g b.w.) administered twice daily to streptozotocin-tr eated mice significantly improved the Embryonic development. Morpholog ical analysis of oocyte maturation in streptozotocin-treated mice show ed no significant differences in comparison with control mice. It coul d be concluded that marked changes in preimplantation embryo developme nt were detected in outbred ICR mice after streptozotocin administrati on and this process was partly reversible by insulin treatment. Furthe rmore, it was shown that the process of fertilization was negatively i nfluenced and that during in vitro cultivation the delayed effects of impaired insulin secretion resulted in an increase of embryo degenerat ion at the time following the third mitotic cleavage.