PARENT SESSION

(T638) REDUCED FOLLICLE DEPLETION AND INCREASED SPERM QUALITY IN AGING MICE SELECTED FOR REPRODUCTIVE LONGEVITY.

MacLaren, Leslie¹, Saccary, Laurelle¹, Logan, Sandra ¹, Farid, A. Hossain¹, ¹ Nova Scotia Agricultural College, Truro, NS, Canada

ABSTRACT- Reproductive senescence is associated with depletion of the follicle pool in the ovary of female mammals and decreased testicular function in males, as well as hypothalamic-pituitary reproductive failure in both sexes. The objectives of the current study were to evaluate follicle depletion and sperm quality in outbred laboratory mice selected for reproductive longevity. The control (C1) and two selected lines, with (SA1) and without (SU1) standardizing for litter size to eight, were established in 1982 and have been continuously selected for extended reproductive life. At generation 24, the SA1 and SU1 lines showed 86% and 61% improvement for reproductive longevity, respectively, compared with the C1 line. For the follicle depletion studies, the right ovaries were collected from females at 3 and 12 months of age (n=6/group) and the number of primordial follicles (PF) determined by histological evaluation of serial sections. Aging was associated with a decline in PF number from 826 ±83 at 3 months to 206 ± 83 at 12 months (LS mean ± standard error; P<0.05). Selection for reproductive longevity was associated with increased follicle numbers at both ages examined (overall LS means 192 vs 698 and 659, respectively, for C1 vs SA1 and SU1; P<0.05). Epididymal sperm characteristics were examined in 12 males from each line at 3 and 12 months of age. There was a line x age interaction, indicating that in control mice, epididymal sperm concentration, % motility and % normal sperm declined more rapidly between 3 and 12 months of age than in selected lines (P<0.05). The results indicate that selection for reproductive longevity is associated with a decrease in the rate of gonadal senescence.

KEY WORDS: gametogenesis, aging, ovary, epididymal sperm