368 THE PHYSIOLOGY OF REPRODUCTION 



have been found in the ovaries of certain of the lower Vertebrates 

 (see p. 145). This resemblance relates chiefly to the hypertrophy of 

 the cells of the follicular epithelium after the discharge of the ova. 

 Such an objection is not to be regarded as a serious one, for there is 

 nothing improbable in the supposition that rudimentary corpora lutea, 

 providing probably some sort of secretion, should have been developed 

 before the acquirement of the function, which, according to Fraenkel's 

 hypothesis, is possessed by the fully formed structure which char- 

 acterises the placental Mammalia. 



Fraenkel has also pointed out, as an argument in favour of his 

 theory, that in ectopic or extra-uterine pregnancy the uterus under- 

 goes the usual changes although there is no ovum in the uterine 

 cavity. It is clear, therefore, that the changes do 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 chorionepitheliomata. 



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 menopause, 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 hypersemia of menstrua- 

 tion, 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 



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

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

 Jour., vol. xvi., 1905. 



