CELL ULTRASTRUCTURE IN MAMMALS 



Fig. 15. Connective tissue of the tracheal submucosa of the rat showing elastic 

 fibers (E), collagen fibrils (C), fibroblasts (F) and reticular fibrils (Re). Magnification 

 24, 000 X 



Reticular fibers. In the light microscope 

 fine fibers are found in loose connective tissue 

 and in the interstitial substance of cartilage 

 which can be elect ively impregnated with 

 silver and they are, therefore, often called 

 argyrophil fibers (Fig. 15). Their submicro- 

 scopic structure is like that of collagenous 



fibers. They have a thickness of about 200 A 

 and have the characteristic cross striations 

 of collagen. In growing tissue it has been 

 demonstrated that the bundles of fibers 

 increase in thickness and finally lose the 

 ability to be impregnated with silver. The 

 reticular fibers found in the interstitial sub- 



109 



