FEMALE ORGANS OF GENERATION 757 



which has not been ascertained. Lymphatics have also been demon- 

 strated at the hilum. 



Graafian Follicles. These vesicles, or follicles, were described and 

 figured by DeGraaf in 1672, and are known by his name. They con- 

 tain the ova, undergo a series of peculiar changes, enlarge, approach the 

 surface of the ovary, and finally are ruptured, discharging their contents 

 into the fimbriated extremity of the Fallopian tube. The Graafian 

 follicles are developed exclusively in the cortical substance. If the 

 ovary is examined at any period of life, no follicles are found in the 

 medullary substance ; but a few of the larger may project downward, so 

 as to encroach somewhat upon it, being actually of a diameter greater 

 than the thickness of the cortex. The entire number of follicles of all 

 sizes in either ovary is about 36,000 (Henle). According to the table of 

 measurements given by Waldeyer, the primordial follicles in the human 

 embryo, at the seventh month, measure ^\- to ^\^ of an inch (30 to 

 100 IJL) in diameter, and the primordial ova, -j^ 1 ^ to TT ^ of an inch 

 (15 to 25/4). 



The ovary appears early in embryonic life, in the form of a cellular 

 outgrowth from the Wolffian body. Most of its cells are small, but as 

 early as the fourth or fifth day, in the chick, some of them are to be 

 distinguished by their large size, their rounded form and the presence 

 of a large nucleus. These cells are supposed to be primordial ova. In 

 the process of development, some of the peripheral cells penetrate in 

 the form of tubes (the so-called ovarian tubes); and at the same time, 

 delicate processes, formed of connective tissue and bloodvessels, extend 

 from the fibrous stroma underlying the epithelium and enclose collec- 

 tions of cells. It is probable that there are two modes of formation of 

 follicles ; one, by the penetration of epithelial tubes from the surface, 

 which become constricted and divided off into closed cavities, and the 

 other, by the extension of fibrous processes from below, which enclose 

 little collections of cells. By both these processes, little cavities are 

 formed, which contain a number of cells. In each of these cavities, 

 there is a single, large, rounded cell, with a large nucleus, this cell be- 

 ing a primordial ovum ; and in addition, in the same cavity, there are 

 other cells, which are the cells of the Graafian follicle. The exact 

 nature of the processes just described has been studied in the chick ; 

 but it is probable that the same kind of development occurs in mam- 

 malia and in the human subject. 



From birth until just before puberty, the cortical substance of the 

 ovary contains several thousands of what are termed primordial follicles 

 enclosing the primordial ova ; and it is probable that after the ovaries 

 are fully developed at birth, no additional ova or Graafian follicles make 



