| Research Abstract |
Age-related changes in ovarian function and morphology were studied in captive Japanese monkeys (Macaca fuscata fuscata), with special reference to reproductive senescence. In experiment 1, a total of 57 nonlactating females at ages 3 to 32 yr were used. Blood samples were collected for at least one breeding season, and changes in plasma concentrations of LH,estradiol and progesterone were examined. In experiment 2, two groups of females (older females, n=5, over 21 yr old, and mature females, n=5 aged 8 to 12 yr) were injected sc with 50 mg/kg of estradiol benzoate during the midbreeding season. Inexperiment 3, ovaries of a total of 47 nonlactating females of various ages ranging from new-borm to <greater than or equal>28 yr old were examined histologically. In experiment 1, ovarian functions as well as fecundity rates were well maintained in the animals aged 5 to 20 yr. Onset of menopause occurred at around 27 yr of age, approaching the end of the life span. In experiment 2 estradiol-treatment elicited an LH surge in both old and mature females. In experiment 3, numbers of primordial follicles per section decreased exponentially with the advance of age, and only a few primordial follicles were observed aftr about 16 yr of age. The numbers of primary and tertiary follicles increased from ages 4 to 16 yr, and then dicreased gradually. About 40% of tertiary follicles were atreticfollicles throughout life, and their size was similar to that of developing tertiary follicles. These results clearly indicate that depletion of oocytes is akey factor in reproductive aging of the Japanes
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