THE MENSTRUAL CYCLE 



even without the corpus luteum a periodic state of estrin 

 deprivation occurs. Can it even be that the adrenal gland 

 produces something that can suppress the estrogens (we 

 know that a number of steroidal compounds resembling pro- 

 gesterone are extractable from that gland) ? The play of 

 hormones in anovulatory menstruation is anybody's guess, 

 and those of us who have worked on it can assure our col- 

 leagues, on the basis of much vain conjecture and many 

 futile experiments of our own, that the problem is not an 

 easy one. Some little fact is lurking just beyond our grasp. 



Since the first draft of this chapter was written, Hisaw 

 has reported from the Harvard zoological laboratory some 

 experiments which show that very small doses of progesterone 

 given and then discontinued (1 milligram a day, for one to 

 five days) will set off menstruation-like bleeding in castrate 

 monkeys which are receiving large daily quantities of estro- 

 genic hormone. He suggests therefore that anovulatory 

 menstruation may be due to progesterone deprivation; even 

 if there is no corpus luteum, he says, there may be a little 

 progesterone produced in Graafian follicles (there is, in 

 fact some collateral evidence for this latter part of the con- 

 jecture) and this may be enough to cause menstruation when 

 such a secretion of progesterone ceases. It is a plausible con- 

 jecture, and one which calls for no new factor outside the 

 ovary ; but it will be difficult to prove. 



The immediate cause of the menstrual process. From the 

 foregoing sections it will be perfectly clear that the break- 

 down and hemorrhage of menstruation are consequent to the 

 deprivation of estrogenic hormone or progesterone. It is 

 also very probable, from the studies of Markee, that these 

 effects are initiated by constriction of the peculiar coiled 

 arteries of the endometrium, which produces damage to the 

 tissues and ultimate degeneration. But how can it be that 

 a temporary deprivation of one of these two particular 

 hormones can shut off the arteries in one particular tissue.'' 



{ 169 } 



