J 68 ELEMENTS OF MAMMALIAN ANATOMY. 



The vagina extends from the uterus to the vestibule, 

 opening on the surface ventrad to the anus. The small 

 papilla just caudad of the orifice of the urethra on the 

 ventral surface of the vestibule is the clitoris, the homo- 

 logue of a part of the penis in the male. The prominent 

 circular fold of mucous membrane craniad of the orifice of 

 the urethra represents the hymen, which marks the separa- 

 tion between the vagina and vestibule. This structure may 

 be shown by making a median longitudinal section through 

 the vagina. Bartholiris glands lie on the lateral aspect of 

 the vestibule, into which their ducts open. Each one is 

 about the size of a small pea. The vagina, uterus, and 

 Fallopian tubes are lined with mucous membrane in which 

 are many glands. The mucous lining is surrounded by a 

 muscular coat especially thick in the uterus. 



The ovaries are the organs producing the female germ 

 cells or ova which when fertilized are known as the eggs 

 (Figs. 55 and 86). One lies caudad of the kidney on each 

 side and is invested by peritoneum, which should be care- 

 fully dissected away. A microscopically prepared section 

 of the adult ovary magnified about 100 diameters will 

 reveal a number of ova in a more or less mature state. 

 Usually a peripheral ring of very young ova is present, 

 more mature ones are near the center, while one or two 

 quite ripe ova are very near the circumference. As the 

 ova develop, a follicle or sac known as the Graafian follicle 

 is formed about them. This is lined with several layers 

 of epithelial cells forming the membrana granulosa. At 

 one side of the follicle the membrana granulosa thickens 

 and envelops the ovum, forming the discus proligerus. The 

 cavity of the follicle is filled with liquor folliculi. When 

 the ovum becomes almost mature, the walls of the follicle 

 have grown peripherad, so as to cause a pin-head pro- 

 tuberance on the surface of the ovary clearly visible to the 



