THE ACTION OF PITUITRIN, ESTRADIOL1 AND PROGESTERONE ON THE HUMAN UTERUS IN VIVO2

Abstract

Investigators are constantly presented with the problem whether physiological responses obtained in one species are directly applicable to another. The impression is current that minor variations in response occur in different species, but that the broader generalized reactions are usually applicable from one species to another. In the following discussion we shall present observations that such generalized principles, when applied to certain phases of the physiology of reproduction, are not directly transferable from the rabbit to the human. The work of Knaus (1), Reynolds and Allen (2, 3), and Corner (4) has established the following facts demonstrating the hormonal control of the rabbit uterus in vivo. 1) Estrone is necessary for the initiation and maintenance of rhythmic motility of the normal uterus. 2) The rabbit uterus is refractory to pituitrin when under the influence of a functioning corpus luteum (in pregnancy or pseudopregnancy). 3) Crude corpus luteum extracts and crystalline progesterone inhibit the estrus mobility and reaction to pituitrin. On the basis of the first two observations Knaus (1) extended his studies to the human uterus in vivo. His method consisted of the insertion of an elastic bag into the uterus, and the recording of the uterine contractions with a suitable kymograph. His conclusions were as follows. 1) In women with a healthy reproductive function who menstruate regularly every 28 to 30 days the uterus manifests spontaneous rhythmical contractions during the first 14 days (before ovulation) and reacts positively to posterior lobe pituitary extract during the whole of this period.