Hydrogen ion and carbon dioxide content of the oviductal fluid of the rhesus monkey (Macaca mulatta).

The pH in the oviduct lumen of adult female rhesus monkey (Macaca mulatta) during the menstrual cycle was measured by means of miniaturized pH electrodes. Two types were used: one was a flexible electrode 1.4 mm in diameter; the other was a rigid electrode 0.8 mm in diameter. The same results were obtained with both types. For PCO2 measurements, the pH electrodes was converted to a Severinghaus tyep electrode covered with a Teflon membrane. During the follicular phase, the pH remains constant in the range 7.1 to 7.3. In association with ovulation, there is a sudden increase in the pH to the range 7.5 to 7.8. The pH remains high through the luteal phase. The PCO2 values obtained showed no evident changes with day of cycle. The range of values estimated was wide because of drift in electrode calibration, with the average level about 89 Torr, compared with 40 Torr for blood. At the average pH of 7.2 in the follicular phase, this value of PCO2 corresponds to 35 mM HCO3-; at the average pH of 7.6 of the secretory phase, this value corresponds to 90 mM HCO3-. This increase in pH and HCO3- after ovulation would be expected to enhance dispersal of corona cells during fertilization and to provide a favorable environment for the developing embryo.