350 ANATOMY AND PHYSIOLOGY 



turn is succeeded by a whitish spot called the corpus albicans. If conception 

 has taken place, the corpus albicans is not formed. The corpus luteum 

 persists, grows larger and remains present until the end of pregnancy. 



The ovary has been included in the list of ductless glands. 

 Its internal secretion is not discovered, but there is undoubted 

 clinical evidence that the corpus luteum contains at least one 

 autocoid substance, since many of the sequelae which follow the 

 removal of the ovaries are prevented by the use of extract of 

 corpus luteum (or lutein). By this means the system is supplied 

 with something of which it had been deprived. (The medicinal 

 extracts are made from the ovaries of swine.) 



THE VAGINA 



The Vagina is the muscular canal extending from the uterus to 

 the surface of the body, where it terminates at the vaginal orifice 

 (Figs. 165, 224). 



It is situated between the base of the bladder in front and the 

 lower portion of the rectum behind, from which organs it is 

 separated by connective tissue septa (vesico-vaginal, and recto- 

 vaginal septa). It curves slightly forward, is four inches long in 

 its posterior wall and about two and three-quarter inches in the 

 anterior. It has two layers of muscles, strengthened by fibrous 

 tissue and lined by mucous membrane which lies in transverse 

 folds. The columns of the vagina are two median ridges, one on 

 the anterior and one on the posterior wall, extending throughout 

 their length. 



The vagina is attached to the cervix of the uterus at a little 

 distance above the external os (about half an inch in front and 

 three-quarters of an inch at the back); therefore the examining 

 finger may feel the cervix projecting into the canal. This is the 

 infra-vaginal portion of the cervix (Fig. 224, 227). The portion 

 of the vagina which is attached to the cervix is ihejornix (or roof). 



Note. ^The urethra lies close to the anterior vaginal wall, feeling like a 

 thick cord in the septum between the two canals (the urethra -vaginal septum). 



LIGAMENTS OF THE UTERUS 



The uterus is sustained in the pelvis by folds of peritoneum 

 which connect it to the pelvic walls and to the bladder and 

 rectum. The principal ones are the broad ligaments (Fig. 224). 



