Features associated with reproductive ageing in female rhesus monkeys

Abstract

Background: The specific aims were to determine the effects of maternal age on the meiotic and developmental competence of oocytes and incidence of chromosomal anomalies in oocytes from a population of fertile rhesus monkeys. Methods: Monkeys were divided into two age groups (4-15 and 16-26 years of age) and underwent ovarian stimulation for collection of oocytes. Results: In the older, compared with younger, monkeys, serum basal concentrations of FSH were elevated (P < 0.05), peak concentrations of estradiol during a stimulation cycle were diminished (P < 0.05), and mean numbers of oocytes retrieved following ovarian stimulation were markedly (P < 0.05) reduced. There were no significant maternal age-related impairments in oocyte maturation, fertilization or blastocyst development. Both abnormal numbers of whole chromosomes, as well as free chromatids, were detected in a limited number of rhesus oocytes. Conclusions: Similarities between female rhesus monkeys and women in several features associated with reproductive ageing, in conjunction with our ability to perform IVF and other assisted reproductive techniques in monkeys, demonstrate the suitability of these animals for studies on human reproductive ageing and maternal age-related infertility. Although maternal age-related impairments in oocytes were not evident prior to implantation, further studies may reveal more subtle impairments, manifested during post-implantation development.