212 



THE ESSENTIALS OF HISTOLOGY. 



Within this is the protoplasm of the cell (vitellus), filled with fatty ami 

 albuminous granules. Lying in the vitellus, generally eccentrically y 

 is the large clear round nucleus (germinal vesicle), which contains an 

 intranuclear network, and usually one well-marked nucleolus (germinal 

 spot). Both the ova and the epithelium of the Graafian follicles are 

 developed originally from the germinal epithelium. In the embryo, 

 this forms a thick layer, covering the fibrous and vascular stroma. 

 After a time solid cords of epithelium-cells, which in some animals are 

 partly tubular (ovarian tubes of Pfliiger), grow down into the stroma, 

 whilst this at the same time grows into the epithelium. The cords 

 presently become broken up by the ingrowths of stroma into small 

 isolated nests of epithelium-cells, each of which may represent a 



FIG. 246. SECTION OF THE OVARY OF A NEWLY BORN CHILD. (Waldeyer.) 

 (Highly magnified.) 



a, ovarian or germinal epithelium ; &, formation of an ovarian tube ; c, c, primordial ova lyinu 

 in the germ-epithelium ; d, d, longer tube becoming constricted so as to form nests of 

 cells ; e, e, larger nests ; /, distinctly formed follicle with ovum and epithelium ; g, </. 

 blood-vessels. 



Graafian follicle. To form the ova, some of the germinal epithelium- 

 cells become enlarged, and usually there is one such enlarged cell in 

 each of the isolated nests. The remaining cells form the epithelium 

 of the follicle (see fig. 246). 



The stroma of the ovary contains, besides the spindle-shaped con- 

 nective-tissue cells and plain muscular fibres already mentioned, a 

 number of epithelium-like interstitial cells, like those found in the 

 intertubular tissue of the testis. They are most abundant near the 

 hilum. Corpora lutea may also be seen in the stroma. These are 

 large yellow nodules, which are developed out of the Graafian follicles 



