The Reproductive System 261 



human beings, the uterus is attached to the body wall chiefly by two liga- 

 ments: the broad and round ligaments. The broad ligaments originate 

 on the lateral margin of the uterus and extend to the pelvis ; the round 

 ligaments have their origin at the lateral angle of the uterus and also ex- 

 tend to the sides of the pelvis. Actually there is great flexibility in the 

 exact position of the uterus, and it is more suspended from than attached 

 to any bony structure. 



The paired Fallopian tubes are located along the upper border of 

 the broad ligaments. Laterally they open into the abdominal cavity in 

 proximity to the ovary. The lumen of the Fallopian tubes is very small 

 and is lined with ciliated epithelium. The beat of these cilia plus some 

 peristaltic waves serves to propel the egg from the ovary to the uterus. 

 It is not entirely clear as to just how the egg gets into the oviduct, but 

 possibly currents set up by the cilia draw it in through the tiny mouth. 

 Fertilization of the ovum normally occurs in the Fallopian tubes and de- 

 velopment is here initiated. 



In human beings, the uterus is an unpaired, pear-shaped, muscular 

 organ. Its cavity is continuous with that of the Fallopian tubes, and it 

 is separated from the vagina by a muscular ridge, the cervix. Histo- 

 logically, the wall of the uterus is composed of three distinct layers : an 

 outer serous or peritoneal layer, a middle smooth muscle layer, and an 

 inner mucous membrane, the endometrium. Implantation and develop- 

 ment of the fertilized ovum occur in the uterus. 



The shape of the uterus varies greatly among the different mam- 

 mals, and is, in general, correlated with the number of young born at one 

 time. In animals, such as the pig, that have multiple births, the uterus 

 consists of a very short body and two horns in which the fetuses develop. 



The unpaired vagina extends from the cervix of the uterus to the 

 urogenital sinus. The wall of the vagina is formed of an inner mucous 

 lining, a middle muscular layer, and an outer connective tissue layer. Its 

 opening is partially closed by a thin connective tissue membrane, the 

 hymen. 



Collectively the external genital organs of the female are known as 

 the vulva. They consist of the mons pubis, a rounded fatty area in front 

 of the pubic symphysis ; the labia major, two longitudinal folds of skin 

 extending from the mons pubis to the anus ; the labia minora, two smaller 

 folds between the labia majora; and the clitoris, which is homologous 

 with the penis of the male. All of these are richly supplied with nerve 

 endings, blood vessels, and sebaceous glands. 



