404 INTERNAL SECRETION 



If the interstitial tissue elaborates the hormone which brings 

 about the uterine changes of menstruation and of rut, it is obvious 

 that this tissue plays a part, first in the nidation, and later in the 

 development, of the fertilized ovum. The assumption of a hyper- 

 function in this direction goes a long way towards explaining the 

 remarkable hypertrophy of the interstitial gland during preg- 

 nancy. 



The further assumption of an antagonism between the inter- 

 stitial cells and the other internal secretory tissues of the ovary 

 in other words, if we assume that the anatomical hypertrophy of 

 the former takes place at the expense of the latter, the hyper- 

 secretion of the interstitial gland being associated with hypo- 

 secretion of the rest of the ovarian tissue accounts for the signs 

 of inhibition of the activity of the ovarian hormone w T hich are 

 observed in other organs during menstruation and pregnancy. 

 The stroma cell-complex affects the cyclic processes in the genitals 

 only, while hormones with other functions are elaborated in the 

 other ovarian tissues. This theory is quite as plausible as the 

 one which has gained credence up to now ; namely, that the 

 phenomena of menstruation, nidation, and development of the 

 fertilized ovum are all promoted by the agency of one tissue- 

 formation, the corpus luteum, which at the same time exercises 

 an inhibitory effect upon other correlative activities. 



This brings us to a consideration of what is known as the 

 corpus luteum hypothesis. 



Prenant (1898) w r as the first to regard the corpus luteum, 

 from the morphological peculiarities of its cellular elements, as 

 a ductless gland, whose peculiar function it is to guard against 

 the interruption of pregnancy, by preventing ovulation during 

 this condition as well as during the intervals between the rutting 

 seasons. 



Gustav Born, the Breslau embryologist, suggested to L. 

 Frankel that, from the nature of its structure and developmental 

 processes, the corpus luteum verum graviditatis is an internal 

 secretory gland whose function it is to establish the ovum in the 

 uterus and promote its development. 



L. Frankel undertook to supply the experimental evidence 

 necessary to the support of this theory. His experiments were 

 conducted with rabbits, the conditions governing their ovulation, 

 impregnation, and nidation being very well known. Rabbits 

 become pregnant every month, and immediately after littering 

 they become pregnant again. If fertilization fails to take place, 

 the rut occurs again at the end of about thirty-five days. The 

 mature Graafian follicles burst soon after littering, when the 

 animal immediately becomes ruttish and impregnation takes place. 

 This act is fruitful ; three hours later the spermatozoa have 

 reached the ovary, seventy hours later the fertilized ova have 

 passed down the Fallopian tubes into the uterus ; upon the fourth 



