138 NORMAL HISTOLOGY. 



cortex are the Graafian follicles, each of which consists of the theca 

 folliculi, composed of an outer and inner coat; the membrana granu- 

 losa, comprising several layers of polyhedral cells; the discus pro- 

 ligerus, the zone of cells surrounding the ovum ; and the ovum, com- 

 prising the zona pellucida, an investing memhrane; vitelline mem- 

 brane, the cell-wall of the ovum; vitellus, the protoplasm of the ovum, 

 which occupies the space between the vitelline membrane and the 

 nucleus; germinal vesicle, which corresponds to the nucleus; and 

 the germinal spot, or nucleolus. 



The number of Graafian follicles in the two ovaries of a child 

 is estimated to be 70,000. The liquid substance within the follicle 

 is the liquor folliculi. When the ovum is ripe it escapes by the 

 bursting of the wall of the follicle, which has gradually approached 

 the surface of the ovary. This makes it possible for the ovum to 

 reach the outside of the ovary, and pass thence to the Fallopian 

 tube. The ovum and Graafian f pllicle are developed from the germ 

 epithelium upon the surface of the ovary. As they develop, they 

 gradually pass into the deeper portion of the cortex. Upon the 

 escape of the ovum, the ruptured follicle becomes filled with poly- 

 hedral cells, which are penetrated by capillaries, and this stage is 

 the corpus luteum. 



The medulla comprises the connective tissue stroma and blood- 

 vessels. 



THE PAROVARIUMisof foetal origin, and is a remnant of 

 the Wolffian body. 



THE FALLOPIAN tubes, or oviducts, convey the ova from 

 the ovary to the uterus. Each tube is composed of three coats (1) 

 the mucous coat, comprising a single layer of ciliated epithelial cells, 

 a tunica propria of connective tissue, muscularis mucosa?, and a 

 small amount of sub-mucous tissue; (2) muscular coat, comprising 

 circular and longitudinal layers; (3) serous coat, derived from the 

 peritoneum, and composed of loose bundles of connective tissue. 



THE UTERUS. This is a continuation of the Fallopian tubes 

 and presents three coats mucous, muscular, and serous. The mu- 

 cous coat consists of a fibrous tunica propria and a simple layer 

 of ciliated epithelium. Toward the cervical end, however, the mu- 



