INTERSTITIAL CELLS OF URODELE TESTIS 



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Fig. 6 Diagrammatic longisections of the testis of Desmognathus to illus- 

 trate the changes, in form and content of the organ, resulting from its slow 

 spermatogenetic wave and delayed lobule regeneration. (A) Early June. (B) 

 Late September. (C) Late November. (D) March. (E) July. The 'bound- 

 ary plane' in each figure is represented by the line immediately above its title 

 letter. To the left of the boundary plane is the region maturing spermatozoa in 

 the first season; to the right of this boundary plane is indicated the region pro- 

 ducing spermatozoa in the following season. Diagrams A and B show the caudo- 

 cephalic movement of the spermatogenetic wave; diagrams C, D, and E illustrate 

 the changes that follow the emptying of a region. 1 , slender cephalic region con- 

 taining only primary spermatogonia; 2, secondary spermatogonia; 3, sperma- 

 tocytes I; 4, divisions of spermatocytes I, and spermatocytes II resting or divid- 

 ing; 5, spermatids; 6, transforming spermatids and immature spermatozoa; 7, 

 mature spermatozoa; 8, emptied lobules degenerating, surrounded by interstitial 

 cells; 9, caudal region from which the interstitial cells have disappeared and 

 only primary spermatogonia appear around the central collecting duct. (Note: 

 The central collecting duct, immediately surrounded by a few primary spermato- 

 gonia, extends throughout the length of the testis. Regions 2 to 8 inclusive, 

 therefore, all contain such primary spermatogonia in addition to the elements 

 indicated above.) 



