FARTHER DEVELOPMENT OF THE OVARY. 



817 



The furtliei* steps in the formation of the ovum, as ascertained by the observa- 

 tions of Foulis, consist mainly in the enlargement of the mass of yolk proto- 

 plasm, the formation of a certain quantity of albuminous and fatty granules in 

 combination with it (deutoplasm of Edw. van Beneden) ; and the formation ex- 

 ternally of the zona pellucida or yolk-membrane by a consolidation cf the outer 



Fig Gil. 







T 



Fig. 611. — Views of the Formation op Ova and Graafian Follicles in the Ovart 



(from Foulis). 

 A, small portion of tlie ovary of a human fcetus of SJ montbs, showing primordial 

 ova imbedded in the stroma ; o, larger primordial ova ; o cluster of earlier ova ; n, fusi- 

 form corpuscles of the stroma. B, portion of the ovary near the surface in a human 

 fcetus of 7 A months, showing the manner of inclusion of the germ epithelium corpuscles 

 in groups in the ovarian stroma ; e, germ epithelium ; e', one of the cells enlarging into a 

 primordial ovum before sinking into the stroma ; o, a larger cell imbedded, becoming an 

 ovum ; o', groups of ovigerms or germ cells which have been surrounded by the stroma. 

 C, young ovum from the same ovaiy, isolated ; p, yolk protoplasm. D, ovum more advanced, 

 enclosed in condensed stroma, wliich begins to form a Graafian follicle ; p, yolk proto- 

 plasm ; V, germinal vesicle with macula ; g, the fusiform corpuscles now converted into 

 the granular cells ; Gf, condensed stroma forming the wall of the Graafian follicle. 



layer of the yolk substance. And here it may be remarked that the recent 

 observations of Oellacher and Balfour on the radiated structure of the yolk proto- 

 plasm may explain in some degree, or be connected with the linear radiated 

 marking of the zona pellucida. 



Such is the number of ova formed in the manner now described, that 

 in the human foetus of six to seven months the whole substanc-e appears 

 to consist of them and their newly formed Graafian follicles, by which 



VOL. II. 



3 G 



