118 THE PHYSIOLOGY OF REPRODUCTION 



that one ovum might undergo development at the expense of the 

 others. Somewhat similar appearances have been observed in 

 the bat's ovary by van Beneden, 1 who regarded them as syncitia 

 from which both ova and follicular epithelial cells took origin. 



On the other hand, KoUiker believed that the follicle-cells 

 arose from the epithelium of the Wolffian body, while Foulis, 2 

 Schron, 3 "Wendeler, 4 and Clark, 5 expressing the opinion that the 

 follicle-cells are derived from the mesoblast, have also dissented 

 from this the more usual view. Clark, in support of his theory, 

 has pointed out that the cells which immediately surround the 

 primordal follicles are often spindle-shaped and similar in ap- 

 pearance to many of the stroma cells, and further, that the 

 primordal ova in the early stages of development are often 

 apparently in direct contact with connective tissue which 

 obviously had been derived from the embryonic mesoblast. 



Most authorities, however (including the more recent in- 

 vestigators), are of opinion that the follicular epithelial cells, 

 in common with the ova, are derived from the germinal 

 epithelium. Further, Miss Lane-Clay pon 6 has recently shown 

 that the epithelioid interstitial cells 7 which (in addition to the 

 connective tissue and plain muscle-fibres) are contained in the 

 ovarian stroma in all probability arise also from the original 

 germinal epithelium. 



The changes involved in the production of ova have been 

 fully investigated by van Winiwarter 8 in the rabbit. These 



1 Van Beneden and Julin, " Observations sur la Maturation," &c., Arch, de 

 Bid., vol. i., 1880. 



2 Foulis, "The Development of the Ova," &c., Jour. Anat. and Phys., 

 vol. xiii., 1876. 



3 Schron, " Beitrag zur Kenntniss der Anatomie und Physiologic des 

 Eierstocks der Saugethiere," Zeitscfi.f. wisscnsch. Zool., vol. xii., 1863. 



4 Wendeler, " Entwickelungsgeschichte und Physiologic der Eierstocke," 

 Martin's Die Krankheiten des Eierstocks und Nebeneierstocks . Leipzig 1899. 



5 Clark, "The Origin, Growth, and Fate of the Corpus Luteum," Johns 

 Hopkins Hospital Reports, vol. vii., 1898. 



6 Lane-Claypon, " On the Origin and Life History of the Interstitial Cells 

 of the Ovary of the Rabbit," Proc. Roy. Soc., ., vol. Ixxvii., 1905. 



7 For a comparative account of the interstitial substance in the ovaries of 

 various mammals, with references to the literature, see Fraenkel, " Vergleichende 

 Histologische Untersuchungen iiber das Vorkommen driis'iger Formationen im 

 Interstitiellen Eierstocksgewebe," Arch. f. Gynak., vol. Ixxv., 1906. 



8 Van Winiwarter, " Recherches sur 1'Ovogenese de 1'Organogenese de 

 1'Ovaire des Mammiferes," Arch, de Biol., vol. xvii., 1900. 



