Biology of Reproduction, Vol 12, 618-631, Copyright © 1975 by Society for the Study of Reproduction

Delayed Fertilization and Preimplantation Loss in Senescent Golden Hamsters

¹ Department of Biology, University of Oregon, Eugene, Oregon 97403

Ova were collected from young virgin (120 animals, 3-5 months of age) and senescent multiparous (172 animals, 14-17 months of age) female golden hamsters from 1 h through 3 days postovulation. The majority of ova recovered from aged hamsters mated with young males exhibited a 2 to 5 h delay in fertilization. This difference was not attributed to delayed ovulation in the older female, but rather to prolonged penetration of the zona pellucida and vitellus by the spermatozoon, extending the time of fertilization. Approximately 40 percent of the ova ovulated by senescent females were non-viable (unfertile, abnormal, and degenerating) at the time of implantation. Many of the non-viable ova could have resulted directly from the aging of the ovum before fertilization, while others appear to be inherently defective at the time of ovulation.