In Vitro Fertilization of Ovulated Rabbit Ova Recovered from the Ovary12

Ovulation times were obtained by direct observation in mature New Zealand white does following intravenous injection of 75 IU of HCG. The average interval between injection and rupture of the first follicle was 10 hr and 35 min. The majority of those follicles destined to ovulate did so by 11.5 hr postinjection. In animals given a single intramuscular injection of 150 IU of PMSG 72–96 hr prior to injection with HCG, the interval between HCG injection and the first ovulation was 10 hr and 7 min, a reduction of approximately 30 mm. Superovulated does were opened approximately 9.5 hr after HCG injection, and the fimbria, including a portion of the ampulla of each fallopian tube, was resected. The abdominal incision was closed until the ovaries were removed 11.5 hr post-HCG. The ova in cumulus were dissected free from each ovary and transferred to a suspension of capacitated spermatozoa. The gametes were incubated under oil at 37–38C in a 5% CO2-in-air atmosphere. Eighty-one per cent of 143 ova were fertilized in vitro. The early cleavage stages appeared later than normally expected. The birth of a live offspring following surgical transfer of ova verified that fertilization occurred in vitro and demonstrated the potential capacity of the ova to undergo subsequent development. The freshly ovulated rabbit ovum recovered from the surface of the ovary has the capacity to be fertilized in vitro and intimate contact of the ovum with the oviduct is not a necessary prerequisite for fertilization in this species.