them as syncitia from which both ova and follicular epithelial cells 

 took origin. 



On the other hand, Kolliker believed that the follicle-cells arose 

 from the epithelium of the Wolffian body, while Foulis, 1 Schron, 2 

 Wendeler, 3 and Clark, 4 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 primordial follicles 

 are often spindle-shaped and similar in appearance to many of the 

 stroma cells, and further, that the primordial 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-Claypon 5 has shown that the epithelioid 

 interstitial cells, 6 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. This 

 has been confirmed by Miss M'llroy, 7 who states that the primordial 



1 Foulis, "The Development of the Ova, etc.," Jour. Anat. and Phys., 

 vol. xiii., 1876. 



2 Schron, "Beitrag zur Kenntniss der Anatomie und Physiologie des 

 Eierstocks der Saugethiere," Zeitsch. f. wissensch. Zool., vol. xii., 1863. 



. 3 Wendeler, "Entwickelungsgeschichte und Physiologie der Eierstocke," 

 Martin's Die Krankheiten des Eierstocks und JVebeneierstocks, Leipzig, 1899. 



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

 Hopkins Hospital Reports, vol. vii., 1898. 



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

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



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

 various Mammals, with references to the literature, see Fraeiikel, " Vergleichende 

 Histologische Untersuchungen iiber das Vorkommen driisiger Formationen im 

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

 to Ancel and Bouin interstitial cells are not present in the ovaries of animals 

 which ovulate spontaneously, the corpus luteum taking their place. (Bouin 

 and Ancel, "Sur les Homologies et la Signification des Glandes a Secretion 

 Interne de 1'Ovaire," C. R. Soc. Biol., vol. Ixvii., 1919.) See also O'Donoghue 

 (" On the Corpora Lutea and the Interstitial Tissue of the Ovary .in Marsupials," 

 Qitar. Jour. Micr. Science, vol. Ixi., 1916), and Cesa-Bianchi (" Osservazione sulla 

 struttura e sulla funzione della cosidetto glandiola interstiziale dell' ovaia," 

 Arch. d. Fis., vol. iv., 1907). The latter author says that there is an inverse 

 relation between the size of the corpus luteum and the development of the 

 interstitial cells in 1 the various species of Mammals ; also that in hibernating 

 animals the interstitial cells are poorly developed during the winter sleep, but 

 during summer and particularly at the time of sexual activity they are very 

 numerous. (See p. 331.) See also Athias, "Recherches sur les Cellules Inter- 

 stitielles de 1'Ovarie des Cheiropteres," Arch, de Biol., vol. xxx., 1919 ; and 

 Rasmussen, "Cyclic Changes in the Interstitial Cells, etc.," Endocrinology, 

 vol. ii., 1918. See also footnote, p. 120. 



7 M'llroy, " The Development of the Germ-Cells in the Mammalian Ovary," 

 Proc. Roy. Soc. Edin., vol. xxxi., 1910. 



