OVUM, CYCLE, AND MENSTRUATION 



ONE FUNDAMENTAL difference between the sexual mechanism in the male 

 and female organisms is of particular importance. While in the male its 

 function is continuous, it is subject to cyclic variation in the female. What 

 are the factors governing these cyclic phenomena? For a long time the theory 

 of the prime importance of the ovum ("Primat cler Eizelle"), advanced par- 

 ticularly by R. Meyer on the grounds of anatomical studies, was generally ac- 

 cepted. This theory implied that the ovary is under the control of the ovum 

 and that the entire generative process receives its stimulus from it; that as 

 soon as fertilization takes place the cycle is discontinued; if, however, the 

 ovum dies without fertilization, the now useless, progestationally developed 

 mucous membrane breaks down and its discharge from the uterus is accom- 

 panied by bleeding (=menstruation). 



This theory, in our opinion, was rather unsatisfactory for the following 

 reasons: (i) It is based on the fact that the death of the ovum, a destructive 

 process, is the event initiating the onset of the new cycle, the menstrual cycle 

 thus being considered a pathological process which takes place only if the 

 ovum does not fulfill its physiological purpose, fertilization. (2) It is difficult 

 to understand how the ovum, dying on its way through one of the tubes, should 

 be able to set in motion the generative mechanism when one considers that 

 it has no contact with the maternal circulation. 



After it had been discovered^"* that a gonadotrophic substance is elaborated 

 in the anterior pituitary lobe and that it is possible to reproduce, experimen- 

 tally, the entire generative process with this factor, the role which the ovum 

 plays within this complex was again open to discussion. It is with great pleasure 

 that I am giving an account of these investigations in the Anniversary Volume 

 published in honor of Herbert M. Evans to whom we owe most important 

 progress in endocrinology, including the problems dealt with in the following 

 lines. 



When attempting to analyze the relationship between the ovum and the 

 hormones involved in the cyclic phenomena, the experimental procedure was 

 to create an opportunity of studying the functions of the ovum independently 

 of hormonal factors and vice versa. 



1. What happens if the function of the ovum is eliminated? Ovular function 

 can be destroyed by Roentgen rays. Investigations on this subject (carried 

 out by Parkes^ and at the same time in our laboratory by v. Schubert*^) yielded 

 the following results: Even the application of doses ten times as high as the 

 castration dose (up to 500 r.) does not interfere with the vaginal estrous cycle 

 in the sexually mature mouse, in fact the cycle may continue for weeks or even 

 months. If such animals are sacrificed in mid-estrus, serial sections show very 

 marked changes in the ovaiy, but— and this is the decisive factor— not one 

 single follicle with a large follicular cavity. One finds only remnants of de- 



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