288 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



F. THE UROGENITAL SYSTEM OF THE MAMMAL 



' Remove the digestive tract, leaving the rectum in place. 



i. The kidneys and ureters. The kidneys of mammals are metanephroi 

 and their ducts the metanephric ducts or ureters. The kidneys are large oval 

 organs situated on the dorsal body wall of the peritoneal cavity. As in all 

 vertebrates they are retroperitoneal. The right kidney is generally considerably 

 anterior to the left one. Clear away fat and connective tissue from about the 

 kidneys. The medial face of each kidney is concave; this concavity is called 

 the hilus. From the hilus a white tube, the ureter, passes out and turns poste- 

 riorly. Follow the ureters caudad, clearing away the fat from about them and 

 note their entrance into the bladder. In females the ureters pass dorsal to the 

 horns of the uterus. In males each passes dorsal to a white cord, the male duct 

 or vas deferens, which loops over the ureter and disappears dorsal to the bladder. 



Remove by a cut the ventral half of a kidney. A cavity, the sinus, is 

 revealed within the hilus; this sinus is occupied chiefly by the renal pelvis, or 

 expanded beginning of the ureter, and also by the renal artery and vein. Into 

 the pelvis the substance of the kidney projects as the renal papilla on which are 

 situated the microscopic openings of the collecting tubules. The kidney sub- 

 stance is readily divided into two areas, a peripheral region, the cortex, and a 

 central region, the medulla. The cortex contains the renal corpuscles and the 

 convoluted and looped portions of the kidney tubules. The medulla is marked 

 by lines which converge to the renal papilla; these lines are the collecting tubules. 

 It will be recalled that the collecting tubules, the pelvis, and the ureter are 

 outgrowths of the Wolffian duct. The collecting tubules and renal papilla 

 together form a pyramid, of which there is but one in the rabbit and cat but 

 about twelve in man. 



Draw. 



The urinary bladder is a pear-shaped sac at the posterior end of the peritoneal 

 cavity. It is ventral to the rectum in the male, ventral to both rectum and 

 uterus in the female. The free anterior end of the bladder is named the apex 

 or vertex, the posterior portion the fundus. The fundus continues posteriorly 

 as a narrowed' stalk, the urethra 1 (also called neck of the bladder). The bladder 

 is covered by the peritoneum, which is continuous with that of the abdominal 

 wall by means of the median and lateral ligaments previously noted. The 

 pouch between the bladder and rectum (male) or bladder and uterus (female) 

 is named the rectovesical or vesicouterine pouch, respectively. 



Draw the excretory system. 



1 The term urethra is in much confusion in comparative anatomy, owing to the differences between 

 the urogenital systems of various mammals. Although in the embryo the urethra is the same as the 

 urogenital sinus, this is not the case in the adults of most mammals, and consequently the use of urethra 

 as synonymous with urogenital sinus appears to be inadvisable. Urethra is therefore here employed 

 in the same sense as in human anatomy, that is, as the name of the duct leading from the bladder to 

 the exterior. 



