GENERATIVE ORGANS OF THE FEMALE 



181 



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 Graafian follicle. 

 To form the ova, some of the germinal epithelium-cells become en- 

 larged, 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. 218). 



FIG. 218. SECTION OF THE OVARY OF A NEWLY BORN CHILD. (Highly magnified.) 



fl, ovarian or germinal epithelium ; 6, formation of an ovarian tube ; c, c, primordial ova lying 

 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, g, 

 blood-vessels. 



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 

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

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

 after the ovum has become extruded. They consist of columns of 

 large yellowish cells, with intervening vascular fibrous tissue, which 

 converge to a central strand of connective tissue occupying the axis of 

 the nodule. The columns of yellow cells are not unlike those of the 

 cortex of the suprarenal capsule. The cells are derived from the 

 membrana graiiulosa of the follicle, which becomes thickened and 

 folded ; between the folds connective tissue and blood-vessels grow in 

 towards the centre, and in this way the corpus luteum becomes 



