166 PHYSIOLOGY OF FARM ANIMALS [CH. 



cells multiply and a space is formed between those immediately 

 covering the ova and the outer cells which are contiguous with 

 the modified connective tissue which forms the outer wall of the 

 follicle. This space is filled with a fluid containing protein sub- 

 stances, etc., the liquor folliculi, which is concerned in the nourish- 

 ment of the ovum. The two portions of follicular epithelium, each 

 of which is several cells deep, are connected by strands of similar 

 cells. Each follicle contains one ovum (rarely two or more) and 

 the largest or most mature follicles may occvipy a considerable 

 part of a section through an ovary; they ma}^ protrude visibly 

 from the surface of that organ and in some animals (sow, etc.), at 

 the approach of the 'heat' periods, the ovary presents almost the 

 appearance of a bunch of small grapes. In addition to follicles 

 the ovaries at certain seasons contain yellow pigmented bodies, or 

 corpora lutea. These, as will be described presently, are formed 

 from the ruptured follicles after the discharge of the ova. Epi- 

 thelioid interstitial cells are also generally present in the stroma. 



The Fallopian Tubes or Oviducts whose function is to con- 

 vey the discharged ova to the interior of the uterus open internally 

 into the body cavity close to each ovary. The ova pass into the 

 fimbriated expansions at the ends of the tubes, which are provided 

 with cilia to direct the passage of the ova. Internally the oviducts 

 are lined by a ciliated epithelium outside of which are connective 

 tissue and muscle. It is believed that the fimbriated ends of the 

 tubes erect at each ovulation In some animals (dog, ferret) the 

 ovaries are enclosed by a membranous covering which is con- 

 tinuous with the wall of the tubes, so as to ensure the discharged 

 ova passing into the tubes and not being lost in the body cavity ^ 



The Uterus. The tubes which are attached to the broad liga- 

 ment (or fold of peritoneum which connects the ovaries and uterus 

 with the body wall) become expanded, passing backwards into the 

 horns of the uterus {cornua uteri). These in many animals (mare, 

 cow, ewe, sow, etc.) unite to form the body of the uterus {corpus 

 uteri) which opens into the vagina or common urogenital passage 

 of the female. The posterior end of the uterus is narrowed down 

 to form the cervix, the actual uterine opening being called the 

 05 uteri. In the rabbit the uterine horns open separately but close 

 together in the vagina. In man the uterine horns are so much 



^ Vestigial structures called the parovarium and paroophoron are found in 

 some animals between the ovary and tube. 



