OVARIAN PROGESTERONE SECRETION DURING THE OESTROUS CYCLE, PREGNANCY AND LACTATION IN DOGS

Abstract

The concentration of progesterone in the ovarian venous blood of female dogs varied between 0.13 and 2.70 [mu]g/h per ovary and per kg body weight, in the different phases of the oestrous cycle. There was no evidence of progesterone secretion in the absence of the corpus luteum. The highest values of progesterone secretion were detected in the early stage of pregnancy (12.9-16.2 [mu]g/h per ovary and per kg body weight). In the course of pregnancy, a gradual decrease in progesterone secretion was found which fell below detectable amounts 48 hours after parturition. The ovarian venous blood did not contain any progesterone in the presence of a corpus luteum of lactation. There was some progesterone in the extracts of placental tissue, however, though in much smaller quantities than in the human placenta.