The Uterus 25 



cornua. In the mare the uterine body becomes relatively more 

 important than in the ruminant. 



The relative importance of the cornua to the uterine body sus- 

 tains a close relation to the number of young brought forth at a 

 given birth. In multiparous animals, there are two uteri, as in the 

 rabbit, or the two extensive cornua with functionally unimportant 

 uterine body, as in the bitch, cat and sow. In ruminants, which 

 are largely bi-parous, the uterine body and cornua become ap- 

 proximately equal in extent and function. 



In the normally uniparous mare, the cornua are smaller than 

 the body, while, in woman, the uterus is virtually without cornua 

 in size or function. 



The uterus and its cornua, within the above limitations, are 

 uniform in their plan of structure and function. They consist of 

 three coats ; mucous, muscular and peritoneal. 



The mucous coat constitutes the essential physiologic basis of 

 the organ. The mucous epithelium is very elaborate, consisting 

 superficially of columnar cells, while, embedded deeply within it, 

 are numerous tubular structures of a glandular character, the 

 utricular glands, believed to secrete the so-called uterine milk, 

 which is presumed to play an important role in the nutrition of 

 the ovum pending the formation of the embryo and the establish- 

 ment of its intricate connection with the mucous membrane 

 through the chorion. Yet more important, it is through a 

 special elaboration of the uterine mucosa that the highly intricate 

 and essential maternal placenta is formed, to constitute a phys- 

 ical and physiologic bond between the mother and fetus dviring 

 the span of pregnancy. The uterine mucosa apparently exerts a 

 distinct bactericidal power and ordinarily prevents the gaining of 

 a habitat by bacteria in the uterine cavity. 



In the non-gravid uterus, as is common with distensible hollow 

 organs, the mucous membrane is thrown into numerous longi- 

 tudinal folds, which permit of prompt and extensive dilation of 

 the cavity without violence to this membrane. 



The muscular coat consists of two somewhat differentiable 

 groups of longitudinal and circular pale muscle fibers which in- 

 crease in size, number and activity during pregnancy. The 

 proportion of the longitudinal to the circular fibers varies, the 

 latter being much more prominent in the region of the cervix. 



