104 



THE NERVOUS TISSUES 



system a special form of sup- 

 porting tissue, the neuroglia, 

 is also found.* 



THE NERVE CELL (cell 

 body, perikaryon, ganglion 

 cell). This term, as already 

 stated, includes the cell body 

 with its dendrites and the 

 proximal portion of its long 

 neuraxis. The cell bodies 

 vary in size from 4 to 200/x, 

 in diameter. Their shape is 

 chiefly dependent upon the 

 number of their processes. 

 Unipolar nerve cells, with 

 but a single process, are flask- 

 shaped or pyriform; bipolar 

 cells, whose processes are usu- 

 ally derived from opposite 

 extremities, are most fre- 

 quently fusiform ; multipolar 

 nerve cells, from the con- 

 siderable number of their 

 processes, are irregularly 

 stellate. 



Nucleus. The cytoplasm 

 of the cell is finely granular, 

 and contains a large vesicular 

 nucleus which, as a rule, is 

 eccentrically situated. The 

 appearance of this large nu- 

 cleus is quite characteristic 

 of the nerve cell, as distin- 

 guished from the cells of 



FIG. 100. DIAGRAM or A NEURONE. 



a Jt, axone hillock ; a x, neuraxis ; c, cytoplasm, the Nissl granules have been stained; 

 d, dendrites ; m, myelin sheath of the nerve fibre ; m', muscle fibre ; n, nucleus ; n', nu- 

 cleolus ; n of w, nucleus of the neurilemma of the nerve fibre ; n .R, node of Ranvier ; 

 s /, collateral ; s L, segment of Lantermann ; tel, telodendrion or terminal arborization 

 which here forms a motor end-plate. (After Barker.) 



See chapter xxiii. 



