144 



ESSENTIALS OF ZOOLOGY 



season and are again withdrawn following it. The testes are oval 

 in shape, being about twice as long as broad. In large fully matured 

 rats the testis may be two centimeters in length. Associated with 

 the testes, in the composition of what is often called the testicle, 



supraienal 



mbaT 



eTer 

 Inteinal^l^eTmatic 

 common iliac 



[)T06Tat 

 fjTosTale 



buiDocaveinosus 



bulbouT 



TecTun 



JDididnmal 

 -TesTiGuIar 



Ljrn[)hL|5i5 bubi6 



cabuT ebidi'dumis 



Testis 



ductus dejeiens 



COT bus ebididumis 



ij^ididy 



mis 



Fig 45. — Lateral view of a dissection showing male urinogenital system of the 

 rat (From Greene, Anatomy of the Rat, Transactions of the American Philosoph- 

 ical Society, New Series, Vol. XXVII, 1935.) 



is the tubular epididymis. The testis is the reproductive gland. It is 

 composed of seminiferous tubules and interstitial tissue. Sperma- 

 tozoa are shed from the inner surface of these tubules where they 



