2OO NORMAL HISTOLOGY. 



ing cells, among which are not infrequently larger 

 and smaller pigmented cells and polyhedral cells 

 resembling epithelium. 



The surface of the organ is covered by a single 

 layer of cylindrical epithelium, whose extreme sig- 

 nificance we shall recognize when we study the de- 

 velopment of the Graafian follicles. The ovary has 

 no serous covering, the peritoneum being replaced 

 by the epithelial cells. 



The interstitial tissue of the ovary is very vascu- 

 lar ; the large arterial trunks, entering from the 

 broad ligament, divide and subdivide in the medul- 

 lary portion, and pass off in larger and smaller 

 twigs into the cortex, from which an abundant 

 capillary net-work is formed around the follicles. 

 The arteries frequently run a very tortuous course, 

 twisting and turning upon themselves, and are char- 

 acterized, moreover, by the great abundance of 

 smooth muscle-cells in their walls. Lymphatic ves- 

 sels are abundant. Concerning the distribution of 

 nerves, our knowledge is still very meagre. 



We have now to consider the structure of the 

 Graafian follicles, to which the parts just described 

 are subservient. The Graafian follicles in the ovary 

 of the adult female, at the child-bearing age, present 

 by no means the same appearance ; some are large 

 and readily visible to the naked eye ; others very 

 minute, and presenting under the microscope an 

 entirely different structure. These differences in 



