THE EHYTHM OF GONADAL FUNCTION 585 



show both hyperplasia and hypertrophy of their epithelial elements, so 

 that during the end of the cycle the glands are thrown into kinks or folds 

 and possess a corkscrew appearance. The glands not only show this great 

 increase in their epithelial elements but also a marked functional activity 

 of the latter as shown by the accumulation of glycogen, fat, lipoids and 

 mucus in their high, cylindrical cells (Ascheim, Wegelin, Driessen, 

 Schroeder, Meyer). These epithelial changes in the uterine glands have 

 been accompanied by changes in the stroma cells, which are also larger 

 and in the middle layers of the endometrium (the so-called spongiosa) are 

 separated by an edematous distention, anastomosing with one another by 

 processes. These enlarged cells of the tunica propria or endometrial 

 stroma look like young decidua cells, and indeed, only slightly more pro- 

 nounced changes would enable them to be termed such. The endometrium 



Corpus luteurr OVulatton 



degenerates 



\ Follicular qrovth, responses in 

 I uterus and vagina (especially 



marked vaginal epithelial hy- Functional life span, of Corpus 



perplasta and desquamaUonj (pseudo-pceanaiuy) 



* RAT 



' , Post-oesircus^' N 



Pr ?~ Oestrus \ante-OYulatory \ 



estrus \ I interval \ . _J 



\ oestrus 



!// A .-*!-*- 12 firs.* 



Corpus luteum 

 degenerates 



IRUteular growth \ functional Ute Span of Corpus luteum, se- 



and endometrlal hyperplasia I eretlon phase of Endomttrtum (pseudo- pregnancy) 



^ A -i A -^ NAN 



Combined oestrous 

 and ante.-ovula.tory periods ^ | 



Ovulatlon 



I* J dqys~\- 10 days -I- IS days 



Fig. 2. Schemata designed to show a comparison of the cyclic ceserous cycle of 

 some mammalia and the human menstrual cycle. 



at the end of the cycle is hence well termed a a pre-gravid" structure and 

 its changes viewed as a contrivance to facilitate implantation. 12 According 

 to Schroeder, the beginning of secretory function on the part of the epi- 

 thelial cells of the glands occurs at about the thirteenth to fifteenth day 

 of the menstrual cycle and is first indicated by the appearance of a clear 

 zone in the basal part of the cell, the nucleus being pushed a little toward 

 the lumen. 



It is of interest that before the discovery of the endometrial cycle any 

 or all of these cyclic transformations in the uterine mucosa were looked 

 upon as pathological. Not the least aspect of the contribution by Hitsch- 

 mann and Adler was its immediate demonstration, for instance, that the 

 so-called endometriiis glandularis hyperplastica of Huge was the normal 

 premenstrual mucosa, that the endometritis exfoliativa was the status ante 



12 Fraenkel has proven the necessity of corpora Intea for implantation. Leo Loeb 

 has made the important discovery that foreign bodies will produce uterine tumors 

 which are astonishing simulations of the maternal placenta and that such responses 

 are dependent on the presence of the corpora lutea, a fact which Corner and Warren 

 and Long and I have been able to abundantly confirm in the rat. 



