Background: The rhesus macaque is an important model to study the effects of environmental toxicants on human reproduction. While the offspring sex ratio is one of the measurements in reproductive studies, this ratio has not been established for rhesus macaques.
Methods: The birth data for the last 23 years at the California National Primate Research Center are reported to determine the post-zygotic sex ratio. The percentage of X- and Y-bearing sperm was evaluated in four males by fluorescence in situ hybridization and by quantitative real-time polymerase chain reaction (QRT-PCR) to determine the pre-zygotic sex ratio.
Results: The total birth data showed a male-to-female offspring sex ratio of 1.03, and the observed ratio of Y- and X-bearing spermatozoa was 1.01. The QRT-PCR failed to provide precise and consistent results.
Conclusions: The offspring sex ratio and sperm X:Y ratio data provide a reference for future studies of the reproductive toxicology in rhesus macaques.