COMPARATIVE ANATOMY OF THE UROGENITAL SYSTEM 285 



tery and has winglike borders which are generally closed together and should be 

 spread apart to see the opening. Trace each oviduct to the cloaca. Each opens 

 into the side of the anterior end of the cloaca, ventral to the opening of the 

 intestine. The stalk of the large bilobed urinary bladder joins the cloaca midway 

 between the two oviducts. 



The cloaca has already been exposed. (If not, do so by cutting through 

 the pelvic girdle on each side and removing the median portion of the girdle.) 

 Clear away connective tissue from around the cloaca. Attached to each side 

 of the cloaca posterior to the oviducts are two elongated sacs, the accessory 

 urinary bladders. Their function is unknown but is possibly respiratory or 

 hydrostatic. A dark structure visible through the wall of the cloaca is the 

 clitoris, homologous with the penis of the male. It is of no use in the female. 



Now cut open the cloaca to one side of the clitoris, extending the cut in the 

 median ventral line up to the stalk of the bladder. Look into the cloaca. 

 Observe that the clitoris consists simply of thickenings in the ventral wall. 

 Find the large openings of the accessory bladders. Next note the opening of 

 the large intestine. This is the most dorsal of the openings and is somewhat 

 separated by a fold from the urogenital openings. Ventral to the opening of 

 the intestine are the openings of the oviducts on thickened papillae. They 

 are best found by cutting into the oviduct and probing posteriorly into the 

 cloaca. Between and ventral to the oviducal openings is the opening of the 

 urinary bladder. 



The kidneys of the turtle are metanephroi. They have already been identified 

 as flattened lobed organs fitting snugly against the posterior end of the pleuro- 

 peritoneal cavity. The renal portal vein and its tributary, the internal iliac, run 

 along the ventral face of each kidney. Dissect off this vein; directly dorsal to 

 it is a tube, the metanephric duct or tireter, extending from the middle of the 

 kidney to the cloaca. It enters the cloaca at the base of the oviduct. By 

 making a slit in it and passing a probe into it its opening into the cloaca will be 

 found just anterior to the thickening caused by the oviducal entrance. 



Draw the female urogenital system with opened cloaca. 



2. The male urogenital system. The male system consists of the paired 

 testes and their ducts. The ducts of the testes are the Wolffian ducts, now called 

 the vasa defer entia. 



Expose the cloaca as directed in the female and find the two accessory 

 bladders attached to its lateral walls. Note the place of attachment of the 

 rectum to the cloaca and ventral to this the attachment of the urinary bladder. 

 The dark mass seen through the ventral wall of the cloaca is the penis or organ 

 of copulation. A rounded mass projects from the anterior wall of the cloaca 

 to either side of the stalk of the bladder; they are parts of the penis and are 

 called the bulbs of the corpora cavernosa. Muscles which retract the penis will 

 be seen attached to the ventral wall of the cloaca. 



