Biology of Reproduction, Vol 1, 149-151, Copyright © 1969 by Society for the Study of Reproduction

Role of Intrauterine Environment on Ova after Normal and Delayed Ovulation

¹ Department of Obstetrics and Gynecology, West Virginia University Medical Center, Morgantown, West Virginia 26506

Blastocysts recovered from control rats or from rats with delayed ovulation were transferred to normal recipients or recipients in which ovulation had been delayed to determine if age of ova and/or altered intrauterine environment affected implanation and subsequent embryonic development. Three types of transfers were made with 20 donor-recipients for each group: transfers in which both donors and recipients were normal; transfers in which the donors were normal and in which ovulation had been delayed in the recipients; transfers in which ovulation had been delayed in the donors whereas the recipients were normal. Recipients were pseudopregnant rats, one group of which had ovulation delayed with pentobarbital sodium. Delayed ovulation in the donor increased the incidence of embryonic death (20.2 vs. 9.4%) and of small or abnormal embryos (19.5 vs. 7.1% of surviving embryos) as compared to control donors, but did not influence the implantation rate (73.2 vs. 72.8%). Blastocysts from control donors had a decreased rate of implantation when transferred to pseudopregnant rats in which ovulation had been delayed (49.7 vs. 72.8% in control recipients), while embryonic development and death were not significantly increased. These data reveal that delaying ovulation decreases implantation rate through changes in the intrauterine environment and that changes in the ovum result in increased embryonic death and developmental defects.