9 



ACTION OF ESTROGEN AND PROGESTERONE 



ON THE REPRODUCTIVE TRACT OF 



LOWER PRIMATES 



Frederick L. Hisaw, Ph.D. 



THE BIOLOGICAL LAB0RAT0RIF:S, HARVARD TNIVERSITY, CAMBRIDGE, 

 MASSACHUSETTS 



and ^ 



Frederick L. Hisaw, Jr., Ph.D. 



DEPARTMENT OF ZOOLOGY, OREGON STATE COLLEGE, CORVALLIS, 

 OREGON 



I. Introduction 556 



II. Ovarian Hormones and Growth of 



THE Genital Tract 558 



III. Effects of Progesterone on the 



Uterus 565 



IV. Synergism between Estrogen and 



Progesterone 567 



V. Experimentally Produced Implan- 

 tation Reactions 571 



VI. The Cervix Uteri 572 



VII. The Vagina 575 



VIII. Sexual Skin 576 



IX. Menstruation 578 



X. The Mechanism of Menstru.^tion. . 583 

 XI. References 586 



I. Introduction 



Cyclic menstruation is the most charac- 

 teristic feature of primate reproduction, and 

 distinguishes it from the estrous cycle of 

 lower mammals. This cardinal primate 

 event is heralded by the bloody uterine 

 effluent emanating from the vagina, whereas 

 in estrus the dominant characteristic is a 

 sudden modification in behavior featuring 

 an intense mating drive. However, the in- 

 ternal secretions that regulate the various 

 events in the menstrual and estrous cycles 

 are the same, and this similarity is funda- 

 mentally more significant than the key de- 

 scriptive differences just mentioned. Estrus 

 comes at the peak of the growth phase of the 

 cycle and is associated with ovulation. In 



contrast, menstruation occurs in the cycle 

 midway between times of ovulation and is 

 not accompanied by an increase in sexual 

 activity. From earliest times menstruation 

 has been recognized as degenerative: the 

 characteristic odor, and the necrotic changes 

 in the lining of the uterus, part of which is 

 cast off at this time, sustain this interpre- 

 tation. Therefore, menstruation is at the 

 opposite phase of the cycle from estrus. It 

 is such an obvious event that menstrual 

 cycles are dated from the onset of bleeding. 

 Menstruation is not analogous to the pro- 

 estrous bleeding in the dog or cow nor to the 

 slight bleeding of primates at midpoint be- 

 tween menstrual periods (Hartman, 1929). 

 The study of menstruation was at first al- 

 most entirely the province of the clinician 

 and the material for investigation limited to 

 w^omen. Hitschmann and Adler (1907), 

 Meyer (1911), Schroder (1914). Novak and 

 Te Linde (1924), and Bartelmez (1933) are 

 among many of the earlier investigators who 

 contributed descriptions of the cyclic 

 changes in the human endometrium. The 

 physiology of the menstrual cycle and at- 

 tendant morphologic changes have contin- 

 ued to be an area of active research interest 

 in science and medicine. Among the many 

 more recent contributors are Bartelmez 



556 



