50 



CONNECTIVE TISSUE CAETILAGE BONE 



other and finally form a syncytial tissue, the mesenchyma, in which 

 there promptly occurs a differentiation of the cytoplasm with the forma- 

 tion of an endoplasm and an exoplasm; and within the latter the fine 

 fibrils soon make their appearance, according to Meves, by processes 

 of fusion and chemical alteration of mitochondria (chondrioconta). 

 This process continues, new ground substance and fibers being con- 



Wz Kolf Kl Elf Plz 



Plb 



Mz 



Kl Kolf 



Elf 



FIG. 57. SUBCUTANEOUS AREOLAR CONNECTIVE TISSUE OF GUINEA PIG. 



(Maximow.) 



Elf, elastic fiber; Kolf, collagenous (white) fiber bundles; Fb, fibroblast (lamellar 

 cell); Mz, mast cell; Wz, resting wandering cell (clasmatocyte) ; Plz, plasma cell; Kl, 

 clasmatocyte ('macrophage'); Eos, eosinophil. X 1750. 



stantly formed at the expense of the endoplasm, until finally the remnant 

 of the latter again forms isolated cells. The culmination of these changes 

 results in the mature fibrillar connective tissue in which the cells are 

 shrunken and scarce, though still apparently capable of assuming renewed 

 activity on demand of altered conditions. The definitive fibrils result in 

 part from a longitudinal splitting of the coarser primitive fibers, collage- 

 nous (Mall), elastic and reticular. 



Embryonic connective tissue is therefore typically cellular as com- 

 pared with the mature type; its ground substance is abundant but the 

 fibers, whose development is as yet incomplete, are scanty. Such embry- 



