Experience with in vitro fertilization of follicular rabbit oocytes and embryo transfer.

Abstract

In vitro fertilization experiments were done in rabbits to develop an effective technique. Preovulatory oocytes were harvested from the follicles of virgin does 9 h after the induction of ovulation by HCG injection and incubated with sperm capacitated in vivo for 5 h. Fertilized ova were cultivated for an additional 20 h until they reached the four- to eight-cell stage. These embryos were transferred to pseudopregnant recipient rabbits who were ‘asynchronous’ in the sense that they had been given HCG injections 6 or 12 h later than the rabbits from whom the ova were obtained. An 81% in vitro fertilization rate of follicular oocytes was achieved. A total of 70 embryos was transferred to the oviducts of eight recipients and 41 young were born. Due to lack of recipients 67 fertilized ova could not be used for transfer experiments.These were cultured for an additional 4–5 days and 44 (66%) developed into blastocysts. Our results were obtained in a consecutive series of experiments and demonstrated that in vitro fertilization can be made to work quite well in the rabbit which, in the early stages of embryogenesis has sufficient similarity with the human, to make it a valuable model for those whishing to acquire techniques applicable to human fertilization in vitro and embryo transfer.