722 



THE REPRODUCTIVE ORGANS 



The Uterine Tubes or Oviducts. The uterine tubes are about 10 

 cm. in length and extend between the ovaries and the upper angles of the 

 uterus. At the point of attachment to the uterus each tube is very narrow; 

 but in its course to the ovary it increases to about 3 mm. in thickness. At 

 its distal extremity, which is free and floating, it bears a number of fimbricr, 

 one of which is longer than the rest and is attached to the ovary. The canal 



FIG. 495. Diagrammatic Representation of a Human Ovum and Its Coverings. 

 (Cunningham.) 



The corona radiata, which completely surrounds the ovum, is represented only in the 

 lower part of the figure. 



1, Corona radiata; $ ; vitellus or yolk; 



2, granular layer; 6, germinal vesicle (nucleus) ; 



3, vitelline membrane; 7, germinal spot (nucleolus); 



4, zona pellucida (oolemma) ; 8, nuclear membrane. 



of the tube is narrow, especially at its point of entrance into the uterus. Its 

 other extremity is wider and opens into the cavity of the abdomen by the 

 fimbriae. The uterine tube is invested with peritoneum, and its canal is 

 lined with ciliated epithelium. 



The Uterus. The uterus, u, c, figure 492, is a somewhat pyriform 

 organ, and is about 7 . 5 cm. in length, 5 cm. in breadth at its upper part 

 or fundus, but at the neck or cervix only about i . 25 cm. The part be- 

 tween the fundus and neck is termed the body of the uterus; it is about 

 2 . 5 cm. in thickness. 



The uterus is constructed of three principal layers, or coats: serous, 

 fibrous and muscular, and mucous. The serous coat, which has the same 

 general structure as the peritoneum, covers the organ except the front surface 

 of the neck. The middle coat is a thick mass of unstriped muscle. The 

 muscle fibers become enormously developed during pregnancy. The arteries 



