34 



Diseases of the Genital Orgajis 



walls are intensely rigid and hard like cartilage. In rigid- 

 ity the cervix is closely analogous to the oviducts. In func- 

 tion, too, they are analogous : the one acts as a powerful 

 guardian of the anterior, or peritoneal opening of the 

 uterus; the other of the posterior, or vaginal portal. The 

 cervix varies in size in the different genera and in individ- 

 uals. The posterior end of the cervix projects into the 

 vagina as an obtuse cone, 11/^ to 21/2 inches in the mare and 



Fig. 15 — Cervices ofVirgin Heifers opened from above on the 

 median line exposing tlie Annular Folds of th.e Slucosa. 



/, First or vaginal fold ; 2, j, 4, the second, third and fourth folds respectively. 



the cow. The cow has the longest and most powerful 

 cervix: it is 3 to 5 inches antero-posteriorly and 2 to 3 

 inches transversely. Its muscular walls are so rigid, and 

 its circular muscle fibres so contracted that it is exceedingly 

 difficult to dilate the canal mechanically, but it dilates freely 

 under the influence of estrum and parturition. The cervix 

 of the mare is shorter than that of the cow and the walls 

 far thinner and more pliable, rendering its canal readily 

 dilatable. 



