340 THE PHYSIOLOGY OF REPRODUCTION 



not occur simply as a consequence of the presence of the 

 ovum. It is also pointed out that in normal pregnancy the 

 uterine changes commence before the ovum enters the uterus. 



Again, the theory that the corpus luteum is responsible for 

 the attachment and early development of the embryo receives 

 some support from those cases in which pathological conditions 

 in the embryo have been found associated with pathological 

 conditions in the corpus luteum. 1 Thus lutein cysts are 

 frequently found in apparent correlation with chorionepi- 

 thehomata. 



Fraenkel's general conclusions regarding the functions of 

 the corpus luteum may be summarised as follows : The corpus 

 luteum is a ductless gland which is renewed every four weeks 

 during reproductive life in the human female, and at different 

 intervals in the various lower Mammals. Strictly speaking, 

 there is only one corpus luteum which represents the ovarian 

 organ of internal secretion, and is regenerated periodically in 

 slightly different positions in the ovaries. Its function is to 

 control the nutrition of the uterus from puberty until the meno- 

 pause, to prevent it from lapsing into the infantile condition or 

 undergoing atrophy, and to prepare its mucous membrane 

 for the maintenance of the ovum. If the ovum be fertilised, 

 the corpus luteum is responsible for maintaining the raised 

 nutrition of the uterus during the first part of gestation. If 

 the ovum be unfertilised it merely produces the hyperasmia of 

 menstruation, and then undergoes degeneration until it is 

 renewed in a fresh position. Since the corpus luteum is, par 

 excellence, the ovarian gland, " lutein " or the extract of this 

 organ, and not preparations of the entire ovary, should be 

 employed for the purposes of ovarian medication. 



Reasons have already been given for concluding that this 

 extended theory of the meaning and function of the corpus 

 luteum is untenable (p. 334). The fact that in a very large 

 number of animals, heat, and presumably, therefore, ovulation, 

 occur at infrequent intervals does not support it, while it has 

 been shown that, in some animals at any rate, ovulation does 



1 Cf. Malcolm Campbell, " Pathological Condition of the Ovaries as a 

 Possible Factor in the Etiology of Uterine Fibroids," Scottish Med. and Surg. 

 Jour., vol. xvi., 1905. 



