154 



PHYSIOLOGY OF FARM ANIMALS 



[CH. 



The vas deferens is the duct conveymg the seminal fluid in 

 which the spermatozoa pass from the epididymis to the urethra. 

 It is hned internally by a non-ciliated columnar epithelium, and 

 its wall contains several layers of .smooth muscle fibres. 







Fig. 76. Section through seminiferous tubules (from Marshall), a base- 

 ment membrane, h spermatogonium, r spermatocyte, d spermatozoa 

 in cavity of tubule, e interstitial tissue containing bloodvessels. 



The Accessory Glands. The semen or fluid discharged through 

 the penis in an ejaculation, is the secretor}^ product of the testis, 

 eiDididjanis, vesiculae seminales and other accessory glands. Near 

 the termination of the vas deferens there is a small sac, the amjndla 

 of He.nle, which also contains small secretory glands but according 

 to Disselhorst its chief function is to act as a seminal reservoir. 



