148 THE PHYSIOLOGY OF REPRODUCTION 



essential particulars. The sheep, however, was found to present 

 some differences from the mouse (as investigated by Sobotta) 

 in regard to the origin of the connective tissue network of the 

 corpus luteum, this being discovered to originate partly from 

 the theca externa, and not merely from the theca interna. It 

 was found also that the cells of the follicular epithelium con- 

 tinued to undergo mitotic division after the rupture of the 

 follicle, but not with the same frequency as previously. The 

 theca interna was stated to become entirely spent in the growth 

 of the connective tissue network. Four days after O3strus the 

 discharged follicle was found to have acquired all the char- 

 acteristics of the fully developed corpus luteum, the luteal cells, 

 as seen in section, being at least six times as large as the original 

 epithelial cells. 



In the same year as the publication of the paper referred to 

 above, on the sheep's corpus luteum, van der Stricht l gave an 

 account of the discharged follicle in bats belonging to the genera 

 Vesperugo, Vespertilio, and Placotus. This was also confirmatory 

 of the conclusion that the follicle cells hypertrophy and give rise 

 to luteal cells, but mitotic division among these cells was also seen 

 to occur. Van der Stricht calls attention to the appearance of 

 fatty particles at a very early stage in the history of the luteal 

 cells. A point of greater importance is that van der Stricht 

 found that, whereas the majority of the luteal cells are derived 

 from the follicular epithelium, a certain relatively small pro- 

 portion of them are developed out of interstitial cells in the 

 inner theca of the connective tissue sheath. This observation 

 lends additional interest to Miss Lane-Claypon's statement that 

 the follicle and interstitial cells have an identical origin, since 

 both are derived from the germinal epithelium, and pass through 

 a similar series of changes. 2 



The structure of the ovary, and the cyclical changes which it 



1 Van der Stricht, " La Rupture du Follicule Ovarique et 1'Histogenese du 

 Corps Jaune," C. R. de I'Assoc. des Anatomistcs, 3rd Session, Lyon, 1901. " La 

 Ponte Ovarique," &c., Bull, de VAcad. Roy. de Medecine Bclyiquc, 1901. 



a Marshall, '_'The Development of the Corpus Luteum : a Review," Quar. 

 Jour. Micr. Science, vol. xlix., 1905. Miss Lane-Claypon's discovery that the 

 follicular epithelial and interstitial cells are probably equipotential may per- 

 haps help to elucidate some of the discrepancies between the accounts by 

 various authors of the formation of the corpus luteum. 



