CHANGES IN ELECTRICAL-IMPEDANCE OF THE VAGINAL MEDIUM DURING THE MENSTRUAL-CYCLE OF FEMALE RHESUS-MONKEYS (MACACA-MULATTA)

Changes in electrical impedance of the vaginal medium during the menstrual cycle were recorded in female Rhesus monkeys using electrical probe and were correlated with estradiol-17-beta and progesterone plasma concentrations. A gradual decrease in impedance was observed during the follicular phase, the lowest values being observed between days 12-17 of the cycle. Impedance increased again during the first third of the luteal phase until day 21. The reversal of the impedance gradient's sign was nearly concomitant with the appearance of a detectable plasma progesterone concentration. These results support the use of vaginal impedance measurements as a help for the diagnosis of the periovulatory time in the female Rhesus monkey.