THE GENITAL GLANDS AND DUCTS — OVARY 



315 



folds of the epithelium are formed, these do not penetrate beyond the tunica 

 albuginea, and all cells derived from this source subsequently degenerate. This 

 new peripheral zone, according to Felix, is always a single cellular mass in man, 

 cords or "Pfliiger's tubes" never growing in from the epithelium. Generally it 

 has been believed that the primary follicles are derived from the subdivision of 

 such cords. 



Coincident with the origin of a new zone of cells at the periphery of the ovary 

 goes the degeneration of young ova in the medulla. By the ingrowth into this 



Primordial ovum 



Germinal epithelium 

 Tunica albuginea 



Pfliiger's egg tubes 



Blood vessel — 8- 



Primordial ova 





Fig. 228. — Ovary of five-months' fetus, showing primordial follicles (De Lee). 



region of connective tissue septa, the ova are separated into clusters or cords, the 

 genital cells of which all degenerate, leaving in the medulla only a stroma of con- 

 nective tissue. Late in fetal life indifferent cells, by surrounding the young ova 

 of the cortex, produce primordial follicles (Fig. 229 A). During the first year 

 after birth the primitive foUicles are transformed into the vesicular {Graafian) 

 follicles. By cell division the follicle cells form a zone many layers deep about 

 the young ovum (Fig. 229 B). Next a cavity appears in the sphere of follicle 

 cells, enlarges, and produces a vesicle filled with fluid (Figs. 3 and 230). The 



