Chap. XXI] THE ORGANS OF GENERATION 445 



(3) Mucous. — The internal, or mucous, coat is arranged in 

 longitudinal folds and covered with ciliated epithelium. It is con- 

 tinuous at the inner end with the mucous lining of the uterus, and 

 at the distal end with the serous lining of the abdominal cavity. 

 This is the only instance in the body in which a mucous and serous 

 lining are continuous with one another. 



Function. — The function of the Fallopian tubes is to convey 

 the ova from the ovaries to the uterus. Just how the ovum, 

 after its discharge into the abdominal cavity, reaches the Fallopian 

 tube is not known. It is thought that the movement of the cilia 

 on the fimbriae and in the tubes produces a current which draws the 

 ovum into the tube. After the ovum enters the tube it is carried 

 to the uterus by the peristaltic action of the tube and the move- 

 ment of the cilia. It is considered probable that many of the ova 

 discharged from the ovaries remain in the abdominal cavity, 

 because of failure to reach the tubes. These ova disintegrate, are 

 absorbed, and carried away by the blood. Occasionally such an 

 ovum becomes impregnated and ectopic gestation results. 



The Uterus. — The uterus is a hollow, pear-shaped organ. In 

 the virgin state it is situated in the pelvic cavity between the blad- 

 der and the rectum. Its length is estimated to be about three inches 

 (75 mm.), its width two inches (50 mm.), and its thickness one inch 

 (25 mm.). During pregnancy the uterus becomes enormously en- 

 larged, attains the length of a foot (300 mm.) or more, measures 

 about eight to ten inches (200 to 250mm.) transversely, and extends 

 into the umbilical region. After parturition the uterus returns to 

 almost its original size, but is always larger than before pregnancy. 

 After the menopause, the uterus becomes smaller and atrophies. 



Divisions. — For purposes of description the uterus is divided 

 into three parts : the fundus, body, and neck. 



The fundus is the convex part above the entrance of the tubes. 



The body is the part between the fundus and the neck. 



The cervix or neck is the lower constricted part and extends from 

 the body of the uterus into the vagina. 



The cavity of the uterus is small ; that part within the body 

 is triangular in shape (v), and has three openings, one at each 

 upper angle, communicating with the Fallopian tubes, and one, the 

 internal orifice, opening into the cavity of the cervix below. The 

 cavitv of the cervix, which is, of course, continuous with the cavity 



