1492 THE OVARY. [BOOK iv. 



adult the peritoneal cavity, the epithelium lining the cavity 

 undergoes a remarkable differentiation. Elsewhere a single layer 

 of flat cells, it here thickens into several layers, the cells being 

 cubical or rounded, and some of them being distinguished from the 

 rest by their size and other features. This thickened area is called 

 "germinal epithelium," the special cells which it contains are 

 "primordial ova," and the patch of differentiated epithelium with 

 the underlying connective tissue becomes the ovary. 



In the course of development the line of demarcation between 

 the epithelial and the mesoblastic or connective tissue elements is 

 broken up by the ingrowth of the one into the other ; and this takes 

 place in such a way that nests of undifferentiated epithelial cells 

 surrounding a primordial ovum, or it may be several ova, are marked 

 out by investments of connective tissue. These nests become what 

 are called Graaffian follicles. A typical Graaffian follicle consists 

 at an early stage of a central cell, which by its relatively large 

 size, ample cell-body and conspicuous nucleus is marked out as an 

 ovum, surrounded by a layer of smaller cubical or columnar or 

 rounded cells, which in turn are enveloped by mesoblastic elements 

 on their way to be developed into vascular connective tissue. The 

 patch of germinal epithelium thus becomes developed into a 

 germinal layer, consisting of a number of Graaffian follicles em- 

 bedded in connective tissue and covered over towards the peritoneal 

 cavity by a single layer of epithelium cells, which by the 'cubical 

 form and more deeply staining cell-substance of its cells is still 

 distinguished as germinal epithelium from the rest of the epi- 

 thelium lining the peritoneal cavity, the cells of which take on 

 the form of flat epithelioid plates ( 289). 



929. In the adult the ovary is an oval swelling, which 

 bulges out from the back of the broad ligament on each side of 

 the uterus, between that organ and the mouth of the Fallopian 

 tube. It is placed with its long axis nearly horizontal, and along 

 the middle of its front surface is attached to the broad ligament 

 by what is called the hilus, the attachment passing at the median 

 end into the ligament of the ovary connecting the ovary with 

 the uterus, and at the opposite outer end becoming connected 

 with the ovarian fimbria of the mouth of the Fallopian tube. 

 Elsewhere the surface projects free into the peritoneal cavity, and 

 is covered with an epithelium which differs from the ordinary 

 epithelium lining the peritoneal cavity by the constituent cells 

 being cubical and granular ; this epithelium is in fact the remains 

 of the germinal epithelium spoken of above. At the attachment 

 of the ovary these cubical cells pass suddenly into the epithelioid 

 plates of the ordinary peritoneal epithelium. 



The body of the ovary consists on the one hand of Graaffian 

 follicles of different sizes and in different phases, and on the 

 other hand of a stroma, or connective tissue basis, in which the 

 former are embedded. The smaller, immature follicles are aggre- 



