Physiology and Endocrinology of the Ovarian Cycle in Macaques
by GERHARD F. WEINBAUER, MARC NIEHOFF, MICHAEL NIEHAUS, SHIELA SRIVASTAV, ANTJE FUCHS, ERIC VAN ESCH, AND J. MARK CLINE
Toxicologic Pathology, 2008, 36: 7S-36S
Abstract:
Macaques provide excellent models for preclinical testing and safety assessment of female reproductive toxicants. Currently, cynomolgus
monkeys are the predominant species for (reproductive) toxicity testing. Marmosets and rhesus monkeys are being used occasionally. The authors
provide a brief review on physiology and endocrinology of the cynomolgus monkey ovarian cycle, practical guidance on assessment and monitoring
of ovarian cyclicity, and new data on effects of social housing on ovarian cyclicity in toxicological studies. In macaques, cycle monitoring is achieved
using daily vaginal smears for menstruation combined with cycle-timed frequent sampling for steroid and peptide hormone analysis. Owing to
requirements of frequent and timed blood sampling, it is not recommended to incorporate these special evaluations into a general toxicity study
design. Marmosets lack external signs of ovarian cyclicity, and cycle monitoring is done by regular determinations of progesterone. Cynomolgus and
marmoset monkeys do not exhibit seasonal variations in ovarian activity, whereas such annual rhythm is pronounced in rhesus monkeys. Studies on
pair- and group-housed cynomolgus monkeys revealed transient alterations in the duration and endocrinology of the ovarian cycle followed by return
to normal cyclicity after approximately six months. This effect is avoided if the animals had contact with each other prior to mingling. These
experiments also demonstrated that synchronization of ovarian cycles did not occur.
by GERHARD F. WEINBAUER, MARC NIEHOFF, MICHAEL NIEHAUS, SHIELA SRIVASTAV, ANTJE FUCHS, ERIC VAN ESCH, AND J. MARK CLINE
Toxicologic Pathology, 2008, 36: 7S-36S
Abstract:
Macaques provide excellent models for preclinical testing and safety assessment of female reproductive toxicants. Currently, cynomolgus
monkeys are the predominant species for (reproductive) toxicity testing. Marmosets and rhesus monkeys are being used occasionally. The authors
provide a brief review on physiology and endocrinology of the cynomolgus monkey ovarian cycle, practical guidance on assessment and monitoring
of ovarian cyclicity, and new data on effects of social housing on ovarian cyclicity in toxicological studies. In macaques, cycle monitoring is achieved
using daily vaginal smears for menstruation combined with cycle-timed frequent sampling for steroid and peptide hormone analysis. Owing to
requirements of frequent and timed blood sampling, it is not recommended to incorporate these special evaluations into a general toxicity study
design. Marmosets lack external signs of ovarian cyclicity, and cycle monitoring is done by regular determinations of progesterone. Cynomolgus and
marmoset monkeys do not exhibit seasonal variations in ovarian activity, whereas such annual rhythm is pronounced in rhesus monkeys. Studies on
pair- and group-housed cynomolgus monkeys revealed transient alterations in the duration and endocrinology of the ovarian cycle followed by return
to normal cyclicity after approximately six months. This effect is avoided if the animals had contact with each other prior to mingling. These
experiments also demonstrated that synchronization of ovarian cycles did not occur.