INTERNAL SECRETION OF OVARY 251 



interstitial cells, the cells of the atretic follicle and those of 

 the corpus luteum. In view of this close relationship it is easy 

 to understand why there are so many terms for the derivatives 

 of the folhcle in the ovary of the mammal and why so many 

 contrary opinions have been held as to the origin of the corpus 

 luteum. 



It would seem that the first of the questions put at the 

 beginning of this section may be settled in a positive sense. 

 The second question, dealing with the physiological relationships 

 between the interstitial tissue and the corpus luteum, will be 

 discussed in the following section. 



(b) The functional relationship between the corpus luteum 

 and the interstitial tissue. 



Different authors, such as Beard, Prenant, and Born, have 

 emphasized that the corpus luteum is a gland with an internal 

 secretion, that the corpus luteum causes by its hormonic action 

 the cyclical uterine changes of menstruation, and the changes 

 which the uterus undergoes in pregnancy. A glance at a 

 microscopical section of the corpus luteum shows that the 

 closest relations between epithelioid cells and blood vessels 

 are present, just as in the liver. And we can fully agree with 

 Fraenkel (1910) that there could, indeed, be no better example 

 to show to the beginner to illustrate the structure of a gland 

 with an internal secretion than the corpus luteum {Fig. 112; see 

 also Fig. 94 a), where each cell is in direct relation with a blood 

 vessel, and for the most part surrounded by blood vessels on 

 every side. Fraenkel (1903) showed that pregnancy can be 

 brought to an end in the rabbit, if the corpora lutea are 

 destroyed by cauterization during the first six days after 

 conception ; a result like that obtained by castration. Fraenkel 

 performed 163 of these experiments, and always with the same 

 result. Further, Fraenkel (1903, p. 480) demonstrated that 

 the next menstruation can be prevented in man by cauteriza- 

 tion of a fresh corpus luteum; Fraenkel made this experiment 

 several times when performing abdominal operations, and he 

 pointed out that such a cauterization is not only without any 

 danger, but may be positively useful, as convalescence is 

 furthered if not interfered with by menstruation too soon. 

 Fraenkel concluded (1903, p. 480) from his experiments that 

 the corpus luteum has in all mammals the same glandular 



