60 



Jeffrey Pudney, Jacob A. Canick, Gloria V. Callard 



they merge gradually, forming a continuum of intermediate stages (see 

 Fig. 5). 



In the cephalic zone the lobules contain a patent lumen throughout 

 their length for the egress of released spermatozoa. These spermatozoa 

 enter the Wolffian ducts where they are stored prior to spermatophore 

 formation (Fig. 9). In the central area of the testis the lobules that have 

 undergone spermiation are often still connected to the immaure por- 

 tions, but at this stage are usually in the process of being pinched off 

 from this part of the lobule (see Fig. 6). Finally, in the caudal zone the 

 degenerating lobular portions become completely separated from the 

 immature regions and reduced in volume owing to the dissolution of the 

 somatic cells by fatty degeneration (see Fig. 7). 



The interlobular tissue surrounding these stages of lobular devel- 

 opment also display dramatic differences in differentiation. Observed by 

 light microscopy, the interlobular cells associated with immature regions 

 of the lobule resemble fibroblasts in their gross morphology. Observed 

 by electron microscropy, however, they have been identified in N. macu- 

 losus as poorly differentiated Leydig cells (Callard et al. 1980). In the 

 cephalic zone the distended, sperm-filled lobules occupy almost the 

 entire volume of this region. This made it difficult to locate and identify 

 the interlobular tissue. When this tissue was studied in N. maculosus by 

 means of electron microscopy, however, it could be seen to be com- 



dz$i>* \ \ 



Fig. 4. Mitotic figures occasionally occur in immature cysts. X 357. 



