Transport of Ova Transferred to Rabbit Oviducts at Varying Intervals after Human Chorionic Gonadotropin Injection

Ova obtained from donors were transfered to the oviducts of New Zealand White rabbits at various times after injection of human chorionic gonadotropin. The rabbits were killed at varying intervals after transfer. The genital tracts were removed, divided into segments (ampulla, isthmus, uterus, and vagina), and flushed to recover the ova. The experiments demonstrated the following: (1) A mechanism is present that retains some of the transferred ova above the ampullary-isthmic junction (AIJ). This mechanism is most efficient 60 hours after hCG injection. (2) Transferred ova that succeed in negotiating the AIJ are found in locations appropriate to the time elapsed from ovulation, rather than from transfer; i.e., they “catch up” to the endogenous ova.