3. The TeBtiottlar Tatules. 



The walls of the tubules of the testis are thin and con- 

 tain flattened nuclei. Figures 1, 2, 3 and 4 are drawings of 

 transverse sections of the tuhules and show different stages 

 In the development of the seminal elements. In Pig. 4 the 

 tubule is seen to be made up of three regions: The smallest 

 one which bordars the more sharply curved side at the bottom 

 of the drawing contains mature sperms. Next to this and fill- 

 ing the central region is a space filled with sperms nearly- 

 mature. The third region, which forms the crescent shaped por- 

 tion on the tipper side, contains spermatocytes in the early 

 propase of the first maturation division. There are more or 

 less definite layers of epithelial cells between the different 

 regions of the tubule. The outer wall and sometimes these 

 inner partitions which border the regions containing mature 

 sperms, become thick and columnar in structure (Pigs. 3 and 

 4). 



Hot only do the seminal elements in these separate paral- 

 lel cavities of the tubule differ in th« stages of their devel- 

 opment but in the same cavity the elements at one end of the 

 tubule are further along in their development than those at 

 the other end. Thus In one end of a cavity the cells may be 

 In the early prophase of the division of the spermatocytes 

 of the first order while in the other end they have reached 

 the spermatid stage. All the stages in the transformation 

 of a spermatid into a sperm may be found in passing from one 

 end of a tubule to the other. 



