CONKM'TIVI-: TISSUE. 



57 



fixed cells sometimes become motile, and wandering cells fixed. 

 They may therefore be classified in three groups on a morpho- 

 logical basis. There are (a) fixed or true connective-tissue cells, 

 (/?) granular cells, (7) wandering cells. 



(a) Fixed or true connective-tissue cells are always flat, usually 

 polygonal cells, which may possess processes and have the 

 appearance of stellate or spindle-like cells (Fig. 29). This last 

 form is found usually in young connective tissue. Looked at 

 from the side, they are like long, thin spindles. The border of 

 the cell is often very thin. In the neighborhood of the nucleus 



FIG. 31. 



fibre 



Xncleux of a 

 tendon cell.. 

 surface rien- 



Ridges on cell ,_--t-2 

 due t<i j)renxiire~~ 



Tendon <<//* xeen ^~~- 

 from edge 



Piece of tendon from tail of white mouse. Between the bundles of connective-tissue 

 fibrils are cells arranged in rows. Some are seen in surface view, and others in optical 

 section. X 400. 



is an accumulation of finely granular protoplasm, which makes 

 the cell thicker at that place. Where they are pressed upon by 

 the fibres of the intercellular substance the cells sometimes show 

 ridges and markings: Often the cells lie in rows on the bundles 

 of fibres (e. g., in tendon) (Fig. 31), where they are disposed 

 longitudinally. The cells may surround the bundles and form 

 more or less complete sheaths for them. By the separation of 

 these cells the isolation of connective-tissue bundles by the 

 action of acetic acid can be explained. On the swelling up of 

 connective-tissue fibres the sheaths formed of connective-tissue 



