38 Diseases of the Genital Organs 



extending from the cervix to the vulva. It begins at the os 

 uteri externum and ends posteriorly at the position of the 

 hymen, just anterior to the meatus urinarius, where the 

 vulva succeeds it. In the cow^, incomplete fusion of the 

 Muellerian ducts in the vaginal segment is evidenced oc- 

 casionally by a muscular column of varying size stretching 

 from the roof to the floor of the vagina on the central line, 

 just against, but free from the vaginal end of the cervix. 



The vagina of the mare is eight to twelve inches in 

 length and capable of lateral distension to the full size of the 

 pelvic cavity. It is lined with squamous epithelium. Its 

 mucosa is thrown into longitudinal folds, which, when at 

 rest, lie in contact with each other. 



The mucous membrane of the vagina has in its deeper 

 portions numerous mucous glands which serve to keep the 

 surface at all times moist and which become especially ac- 

 tive during sexual excitement and at the close of pregnancy. 

 The muscular coat does not differ fundamentally in arrange- 

 ment from that of the uterus, though less in volume. 



In the mare, the peritoneal covering extends backward 

 from the anterior extremity three to five inches, where it 

 becomes reflected upon the rectum, bladder, and pelvic walls. 

 In the posterior portion of. its course, the vagina is sur- 

 rounded by the loose pelvic connective tissue, which permits 

 comparatively free movement. 



The function of the vagina is chiefly copulative, receiving 

 the penis of the male during coition. During parturition, 

 it affords a passage for the fetus from the uterus to the 

 vulva. 



In the mare and the cow the vagina frequently becomes 

 ballooned during manual exploration of the organ, owing to 

 an inflow of air at the moment of inspiration. During ex- 

 ploration the vulva is propped open by the hand or arm of 

 the operator, permitting the air to flow in, distending the 

 vagina so that it fills the pelvic cavity completely from side 

 to side and from roof to floor, presenting a vast cavity with 

 smooth, rigid walls, which are in close contact laterally with 

 the bony or ligamentous, pelvic walls, superiorly with the 



