68o Ovum, Cycle, and Menstruation 



generated ova, but none appear to have survived. The cycle as well as the 

 estrous development of the mucous membrane, therefore, takes place in the 

 absence of functioning ova. Similar results were obtained by giving an irri- 

 tation dose to the infantile ovary (ref. 7, p. 60, 317). Small Roentgen doses 

 (10-25 ^■) ^^^ ^ble to stimulate follicular growth so that the follicle may be 

 developed to the size of a Graafian follicle just before rupturing. No estrogenic 

 hormone is, however, elaborated in these follicles in which growth but no 

 function has been induced. Morphologically, the ova present in these follicles 

 are not to be distinguished from those of normal mature animals. Thus, al- 

 though the follicle is large and contains ripening ova, no estrogenic hormone 

 is produced there and the ripening follicle with its ovum is obviously unable 

 to initiate the production of hormone. 



2. Does estrogenic hormone stimulate follicular maturation? This question 

 has to be answered in the negative. Estrus can be produced in infantile ani- 

 mals with estrogenic hormone, but no follicvdar maturation takes place. The 

 gonadotrophic hormone— as is well known— initiates both the production of 

 estrogenic hormone and the ripening process in the follicle. The production of 

 estrogenic hormone is, however, already accomplished (in the twenty-seventh 

 hour) before the growth and maturation of the follicle has even started.*®'^" 



3. Does the ovum stimulate corpus luteum formation? Does it produce sub- 

 stances likely to initiate the second generative phase? That this is not the case 

 is clearly shown by the following experiments: (a) In hibernating animals 

 ovarian function slumbers too. It was, however, possible to achieve follicixlar 

 rupture in hibernating bats in winter (ref. 11; also ref. 7, p. 267); in one case 

 pregnancy was obtained in December. (In the bat, as is generally known, 

 copulation takes place previous to hibernation, the living spermatozoa remain- 

 ing in the uterus all the time.) If large doses of prolan are injected into such 

 animals, the formation of several corpora lutea is thus initiated (4-6 in one 

 ovary). (This never occurs under physiological conditions since the bat usually 

 has one young, at the most two.) Large doses may give rise to the formation of 

 corpora lutea atretica in which the ovum is completely pushed aside and, 

 seemingly crushed. No signs of ripening are recognizable in these ova. Not- 

 withstanding the death of these ova, normally functioning corpora lutea ap- 

 pear, as is seen from the effect on the uterine mucous membrane. The ovum 

 cannot, therefore, be held responsible for corpus luteum formation, (b) It 

 could be imagined that the ovum, although dead at this stage, might pre- 

 viously have produced a hormone active in bringing about corpus luteum for- 

 mation. That neither is the case could be demonstrated by Westmann's and 

 later by our experiments'"'^^ conducted on the follicles of rabbits from which 

 the ova had been removed. In our experiments the procedure was to extirpate 

 one entire ovary in sexually mature rabbits, while in the other the ovarian 

 tissue was cut down to such an extent that only a small portion remained, 

 containing just a single follicle on the point of rupturing. This follicle was 

 then punctured and the ovum aspirated. By microscopical examination ol 



