ABSTRACT
Ovariectomized mature rhesus monkeys (n = 5) were given daily injections of oestrone (synonym: estrone, an estrogen) for 14 days. Erythrocyte counts were performed twice each week, and the subjects were observed for uterine bleeding to indicate the onset of the following cycle at which time the regimen of hormone administration was repeated (Guthkelch and Zuckerman 1937). Two cycles were monitored with the second program of injections starting on the second day of bleeding. Consistent with the pattern observed in intact healthy mature macaques undergoing the follicular phase of the menstrual cycle, the oestrone-injected ovariectomized subjects demonstrated an increase in the Rbc count during the course of the injections. After cessation of the administration of the hormone, the red cell count gradually fell during the period that intervened between the cessation of injections and the onset of uterine bleeding. A second increase in the red cell count was observed before uterine bleeding in six of nine experiments. The erythrocyte counts during the investigation (n = 5, 9 cycles of injections) were the following. The mean erythrocyte count during the rst week of injections of a given cycle was 4.86 × 106/µL; the mean maximum during the second week of injections
was 5.67 × 106/µL. The average minimum count during the latent period prior to bleeding was 4.83 × 106/µL, while the mean red cell count at the onset of bleeding was 4.98 × 106/µL. The studies of intact normal monkeys demonstrating menstrual cycles and oestrone-injected ovariectomized counterparts demonstrated that the erythrocyte count is lowest at the beginning and end of the menstrual cycle. It is highest in the middle of the cycle. The fall in the red cell count coincides with the time of ovulation. The variation of the red cell count is believed to be due to hemoconcentration secondary to hormonal inuence. The latter concept is supported by comparable investigations in the pig-tailed monkey.
