SPERMATOZOA. 



273 



ture of the products of the epididymis, vesicles, prostate and bulbo-ure- 

 thral glands. Then by an undulating movement of the tail the head is 

 propelled against such a current as is made by a cilia, at a rate of | of 

 an inch in a minute. Water inhibits the motion, which is favored by alka- 

 line fluids; it occurs also in those faintly acid. Spermatozoa may retain 

 their activity three days after death and in the female urogenital tract 

 they may live a week or more. In addition to normal spermatozoa, 



*'^~~* **-~~'' t -~ ' 



L-A 



FIG. 310. SECTION OF THE HUMAN RETE TESTIS. X 96. (Kolliker.) 



A, Artery; C, rete tubules; L, lymphatic vessels; s, connective tissue partly surrounded by rete tubules;. 

 Sk, part of a convoluted tubule, to the left of which are sections, probably of straight tubules; v, vein. 

 (From Bailey's "Histology.") 



giant forms and some with two heads or two tails occur, but these are 

 of unknown significance. 



The convoluted tubules of the testis consist therefore of a complex 

 stratified ciliated epithelium, the basal cells being spermatogonia and the 

 superficial cells, spermatozoa. The columnar sustentacular cells are 

 scattered through this epithelium. Spermatogenesis occurs in "waves" 

 along these tubules as is seen when they are cut lengthwise (Fig. 309). 

 18 ^ 



