218 DR. JAMES FOULIS. 



proliferation from those columnar corpuscles which invest the 

 median side or surface of the Wolffian body, and which are 

 continuous with the layer of columnar corpuscles that lines the 

 pleuro-peritoneal cavity of the embryo in the early stages of 

 development. The stroma of the ovary in the early stages 

 of development is produced by a direct growth out from the 

 interstitial tissue of the Wolffian body immediately beneath 

 the germ epithelium on the median side of the Wolffian 

 body. 



The germ epithelial corpuscles proliferate by fission. In 

 the human foetal ovary of 7^ months they measure -j-^^'^iyth 

 to -TToiJ-ot^ o^ a^i i^ch in their longest diameter, and about 

 3 a\, „ th of an inch in their shortest diameter. Eath germ 

 epithelial corpuscle is a nucleus surrounded by a thin film or 

 investment of clear protoplasm. In the act of becoming 

 primordial ova, the nucleus of each germ epithelial corpuscle 

 swells up into a spherical body, within which is generally 

 seen a nucleolus, and around which is produced clear homo- 

 geneous protoplasm which subsequently forms the yelk of the 

 ovum. Germ epithelial corpuscles are seen on the surface of 

 the ovary in all stages of development into primordial ova. 

 In each primordial ovum the spherical germinal vesicle pre- 

 sent a sharply defined limiting membranous wall. Within 

 the germinal vesicle is the nucleolus or germinal spot. All 

 the ova in the ovary are derived from germ epithelial 

 corpuscles. 



In all parts of the germ epithelium processes of vascular 

 connective tissue stroma grow in between and around 

 certain of the germ epithelial corpuscles, whereby the latter 

 become more and more imbedded in the stroma of the ovary. 

 Germ epithelial corpuscles are being constantly produced on 

 the surface of the ovary, to take the place of those already 

 imbedded in the stroma. The imbedded corpuscles increase 

 in number by division, and the nucleus of each swells up 

 into a spherical germinal vesicle, around which is gradually 

 produced the yelk of the ovum. In all parts of the young 

 ovary under the germ epithelium, groups of germ epithelial 

 corpuscles become imbedded in meshes of the stroma. As 

 each individual in the group swells up the nucleus or germinal 

 vesicle becomes very distinct as a round or spherical body. 

 From the swelling out of each germ epithelial corpuscle in 

 the group, the whole group expands and becomes more or 

 less spherical. Such groups of developing corpuscles are 

 called egg clusters. Each egg cluster is enclosed in a mesh 

 or capsule of vascular stroma of the ovary. Each imbedded 

 germ epithelial corpuscle is potentially an ovum. 



