Ovarian morphological and functional changes in reproductively senescent hamsters

Ovaries from young and senescent hamsters were examined morphologically on days 8, 12 and 14 of pregnancy to determine if there were any differences between the two age groups. The senescent hamsters had fewer follicles present than the young on all days of gestation. The senescent females' corpora lutea experienced the greatest growth between days 8 to 12, whereas corpora lutea from young animals grew the most between days 12 and 14. Corpora lutea in senescent females did not grow at all between days 12 and 14. The lower number of follicles in senescent females was not due to the lower rate of implantation. Superovulation with PMS revealed that the senescent ovary was refractory. It was concluded that there are quantitative not qualitative differences between ovaries from young and senescent hamsters during pregnancy. The refractory ovary of senescent females could be contributing to pregnancy wastage in this species by secreting less progesterone.