1994 



HUMAN ANATOMY. 



Fig. 1693. 



Germinal epithelium 



Primordial ovum 



Ova 



multitudes of the smaller and less specialized cells of the germinal epithelium. The 

 larger tracts are subdivided into smaller spherical cell-aggregations (the egg-balls 

 of Waldeyer) by the continued intergrovvth and mutual invasion of the tissues, and 

 the " egg-balls," in turn, are broken up by the same process until the final division 

 results in the isolation of the ultimate groups, the primary follicles, that include the 

 primary ova surrounded by a single layer of flattened germinal epithelium. In 

 places the larger compartments are cylindrical and attached to the germinal epithe- 

 lium, appearing as solid outgrowths connected with the surface ; to them Pfiiiger 

 gave the name "egg-tubes" and attributed an aggressive invasion. Since the con- 

 nective tissue of the Wolffian stroma first invades the deeper stratum of the germinal 



epithelium, this region, the fu- 

 ture medulla of the ovary, is 

 subdivided into the ultimate 

 groups of cells, the primary fol- 

 licles, earlier than the more su- 

 perficial and younger layers, 

 this genetic relation being seen 

 in the fully developed ovary, in 

 which the youngest and least 

 mature follicles always occupy 

 the peripheral zone. The most 

 superficial stratum of the ger- 

 minal ridge remains as the ger- 

 minal epithelium that covers 

 the exterior of the ovary and 

 replaces the usual peritoneal 

 mesothelium plates. 



The details of the trans- 

 formation of the primary folli- 

 cles, consisting of the ovum and 

 the investing single layer of 

 mantel-cells, into the ripening 

 Graafian follicles have been de- 

 scribed (page 1988). Of the 

 thousands of primary follicles 

 within the young ovary (over- 

 estimated by Waldeyer at 

 100,000 in the two ovaries of 

 the new-born child) very few reach maturity, and by advanced life nearly all have 

 disappeared. This reduction begins during intrauterine life and first affects the fol- 

 licles situated within the deeper parts of the ovary destined to become the medulla, 

 from which the ova are later entirely absent. The remains of these early follicles 

 probably account for certain of the minute epithelial bodies occasionally seen in the 

 medulla of young adults. 



Ovarian 

 stroma 



Section of developing ovary from human embryo, 

 showing intergrowth between germinal epithelium and 

 stroma tissue derived from Wolffian body. ■; 560. 



Numbers of follicles within the cortex also are continually undergoing destruction. This 

 affects especially the primary follicles while they lie naked within the stroma, and are unpro- 

 vided with a theca, the ovum undergoing hyaline degeneration and, along with the mantel- 

 cells, finally entirely disappearing within the ovarian stroma. Beginning in the young ovary 

 long before puberty, as well as throughout the period of sexual maturity, certain egg-sacs are 

 continually transformed, more or less fully, into Graafian follicles that develop to a certain 

 stage and are then arrested, after which they enter upon regression, degenerate, and finally may 

 completely disappear. This process, known as atresia of the follicles, is probably closely 

 related to alterations in their blood-supply (Clark). 



With possibly few exceptions, the formation of new follicles ceases during the first few 

 years after birth, the supply developed early in life being in such lavish excess of all possible 

 needs that ample provision is made against dearth of reproductive cells. Infrequently 

 follicles are encountered in which two or more ova are present. This condition results from 

 the inclusion of more than a single primary Q'y^ when the follicle was formed, and not from 

 division of an ovum already enclosed, since after the mantel-cells surround the ovum it is 



