THE CORPUS LUTEUM 723 



of their ovulation, which may be either spontaneous or not. 

 According to Ancel and Bouin (1) in animals in which ovulation 

 is not spontaneous, i.e. it requires the additional stimulus of 

 coition to provoke it, only one kind of corpus luteum is to be 

 found, the " corpus luteum gestative" and this body, however 

 produced, always becomes fully grown and is of long duration. 

 In the remaining mammals, where ovulation occurs spon- 

 taneously, two varieties of corpora are encountered. Firstly, 

 during each pregnancy a " corpus luteum gestative " is formed 

 similar to that in the preceding group. Secondly, in non- 

 pregnant females at each heat period corpora lutea are formed. 

 These do not become full-grown and have but a transitory 

 existence and are termed " corpora lutea pe'riodiques." This does 

 not appear to apply universally however, for in a Marsupial 

 (Dasyurus (15)), 1 although the ovulation is spontaneous, it is 

 not possible to distinguish between the corpora lutea in the 

 pregnant and non-pregnant females. 



It is perhaps better to retain the terminology in use before 

 the work of Ancel and Bouin, as it applies equally well to either 

 group of mammals. Thus : 



The corpus luteum verum is the structure that forms in the 

 ruptured follicle in the ovary of a female when pregnancy follows 

 ovulation. 



The corpus luteum spurium is the structure that forms in the 

 ruptured follicle in the ovary of a female when ovulation is not 

 followed by pregnancy. 



Still another term is to be found in older works, namely 

 corpus luteum atreticum. It is applied to an ////ruptured follicle 

 undergoing atrophy, i.e. an atresic follicle, and as it is not 

 comparable in structure with either of the foregoing it will not 

 be dealt with here. 



Growth and Structure of the Corpus Luteum Verum 



Immediately after the discharge of the ovum the follicle 

 shrinks considerably. In some animals the cells of the 

 membrana granulosa come together so as to close the point 

 of rupture by a plug of epithelial cells (Bouchon epithelial), 

 while in others apparently the opening may persist for some 

 time. The interior of the body which is now a corpus luteum 



1 This has since been shown to be the case in certain other marsupials (i6a). 



