Nonhuman Primate Models of Menopause (Part 6)

Several reproductive indices measured in wild baboons were similar to those measured in captive animals (unpublished data from the Southwest Foundation for Biomedical Research). Wild and captive baboons both had the same exponential trajectory of adult mortality. Both populations were completely infertile at 25 yr of age. The mean menstrual cycle length for both is constant from 5 to 20 yr of age (~38 days in the wild and ~33 days in captive populations). However, some differences between the wild and captive baboons were evident. A longer peak fertile period occurred in the wild (5-21 yr of age) relative to the captive animals (7-17 yr of age), which is likely due, at least in part, to husbandry practices that limit opportunities for mating in the captive population. Wild animals showed an abrupt decline in fertility, whereas captive animals showed a more gradual decline. Mean cycle irregularity markedly increased at 19 yr in captive animals, compared to 23 yr in wild baboons. In 18 captive baboons who survived beyond 24 yr, the mean age at menopause was 26.3 yr and the mean perimenopausal duration 7.4 yr, similar to humans. natural asthma treatment

Chimpanzee. To our knowledge, only two studies examining hormonal changes in very old female chimpanzees have been published. The general conclusion based on the study of only 12 animals is that Pan troglodytes have menstrual cycles right up to the end of life, or that cycles terminate only within the last year of life. A small decline in cycle frequency occurred in animals older than 35 yr (8.6 cycles/yr) relative to animals from 15 to 25 yr (9.5 cycles/yr); the cycle length was longer in the older animals (35.6 vs. 32.2 days/cycle).

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