EXCRETORY AND REPRODUCTIVE SYSTEMS 20I 



the kidneys, against the dorsal abdominal wall. From the vicin- 

 ity of each extends a tube caudad to join its fellows in the median 

 line ventrad to the rectum (Hgs. 6i and 97). The cranial por- 

 tions of these are the uterine tubes, and the larger caudal portions 

 are the cornua of the uterus. The junction of the cornua in 

 the median line forms the body of the uterus. 



The uterine tube is smaller in diameter than the cornu of the 

 uterus, generally more or less contorted, and terminates by a 

 fimbriated expansion or mouth opening freely into the 

 abdominal cavity. 



The uterine tubes and uterus are suspended by the broad 

 ligament, or ligamentum latum, which is a fold of the perito- 

 neum attached to the dorsal abdominal wall. The round liga- 

 ment, or ligamentum rotundum, also aids in keeping the uterus 

 in place. This appears as a thickening of the broad ligament 

 when the latter is looked through toward the light. The round 

 Hgament extends from about the middle of the horn or cornu of 

 the uterus ventrad of Poupart's ligament, and through the mus- 

 cles of the abdominal wall beneath the skin of the inguinal 

 region, where it gradually loses itself. It is exceedingly delicate 

 and thread-like. During pregnancy a portion of the uterine wall 

 becomes very vascular and undergoes other important changes. 

 It unites with the chorion of the fetus to form the placenta. 

 The blood-vessels of both parts of the placenta, maternal and 

 fetal, interlace but do not directly communicate with each other. 

 It is through the placental blood-vessels that the fetus receives 

 its nourishment and oxygen. 



The vagina extends from the uterus to the vestibule, opening 

 on the surface ventrad to the anus. The small papilla just 

 caudad of the orifice of the urethra on the ventral surface 

 of the vestibule is the clitoris, the homologue of a part of the 

 penis in the male. The prominent circular fold of mucous 

 membrane craniad of the orifice of the urethra represents 

 the hymen, which marks the separation between the vagina 

 and vestibule. This structure may be shown by making a 



