CHANGES IN THE OVARY 149 



In man the corpus luteum eventually loses its colour, becoming 

 converted into the so-called corpus albicans, after which ifc is described 

 as becoming merged into the connective tissue of the ovary. 



The corpus luteum of pregnancy is sometimes distinguished from 

 the structure formed when pregnancy does not supervene after 

 ovulation, the latter being called the false corpus luteum, 1 or corpus 

 luteum of menstruation ; but it is obvious that the two bodies are 

 identical in the early stages, and otherwise essentially similar. 2 

 According to Ancel and Bouin, 3 in animals like the rabbit, which do 

 not ovulate spontaneoiisly during oestrus, these two kinds of corpora 

 lutea are identical throughout. In such animals interstitial cells are 

 believed to replace functionally the "periodic corpus luteum." 

 Hammond, 4 however, as just remarked, has shown that the two kinds 

 of corpora lutea in the rabbit are not identical in size, but that 

 the organs formed under experimental conditions (corpora lutea of 

 pseudo-pregnancy, see p. 101) do not become so large as the corpora 

 lutea of pregnancy. 



Watson, 5 and Long and Evans, 6 have described a corpus luteum 

 of lactation in the rat, but Hammond states that a study of suckling 

 rabbits' ovaries does not confirm this, but that nevertheless the 

 corpora lutea may persist for some days after pregnancy terminates 

 (see below, p. 622). 



The hypotheses which have been put forward regarding the 

 function of the corpus luteurn, and the possible part which this organ 

 plays in the metabolism of pregnancy, will be discussed at some 

 length in a future chapter. (For chemistry of corpus luteum see 

 p. 273.) 



THE ATRETIC FOLLICLE 



It has been already mentioned that the rabbit, the ferret, and 

 certain other animals do not necessarily ovulate during oestrus in the 

 absence of the male. The follicles, instead of bursting, undergo 

 degeneration (atresia) with their contained ova. Heape 7 has shown 

 that the congested vessels in the wall of the follicle may rupture and 



1 Or corpus luteum spurium. 



2 The retrogressive changes are similar in both kinds of corpora lutea. 



3 Ancel and Bouin, " Sur les Homologies et la Significance des Glandes a 

 Secretion interne de 1'Ovaire," C. If. de la Soc. de Biol., vol. Ixvi., 1909. 



4 Hammond, " On the Causes Responsible for the Developmental Progress 

 of the Mammary Glands in the Rabbit during the latter part of Pregnancy," 

 Proc. Roy. Soc., B^ vol. Ixxxix., 1917. This author bases his statements on a 

 number of careful measurements which are duly recorded. 



6 Watson (B. P.), "On the State of the Ovaries during Lactation," Proc. 

 Physiol. Soc., Jour, of Physiol., vol. xxxiv., 1906. 



6 Long and Evans, " The CEstrous Cycle in the Rat, and other Studies in 

 the Physiology of Reproduction," Anat. Record, vol. xviii., 1920. 



7 Heape, " Ovulation, etc.," Proc. Roy. Sot:, B., vol. Ixxvi., 1905. 



