7i6 



THE REPRODUCTIVE ORGANS 



The important stages in order are: archispermiocyte, spermatogonia, 

 primary and secondary spermatocytes, spermatids, and spermatozoa. The 

 spermatogonia stage is the stage of rapid multiplication; the spermatocyte, 

 that of maturation, comparable to the maturation stage of the ovum. 



The sperm cells are the essential male reproductive cells. Each sperma- 

 tozoon consists of a minute oval head, a middle piece, and a tail. The head 



spd 



spc.t 



spg.r 



FIG. 488. Later Stages in Spermatogenesis of the Bull, spg.r, Reserve spermato- 

 gonium; spg, spermatogonium; spc.g, spermatocyte in late synapsis stage; spc.i, spermacyte 

 in stage just preceding the maturation divisions; spd, spermatids in advanced stage of 

 histogenesis, with heads deeply embedded in Sertoli cell. Highly magnified. (After 

 Schoenfeld.) 



is 4/* by 2 . 5/. The middle piece and tail are about 50 to 6o/j. long. Sperm 

 cells possess the power of flagellate movement. 



The Ductus Deferens. This is the single duct proceeding from each 

 testicle to join its fellow at the base of the bladder. Each has an ampulla or 

 enlargement just before it unites with its fellow. The ductus deferens has 

 muscular walls and is lined with ciliated epithelial cells. 



The Vesiculae Seminales. The seminal vesicles have the appearance 

 of outgrowths from the base of the deferent ducts. Each deferent duct 



