NERVE TISSUE 



147 



neurones, and spongioblasts or future neuroglia cells, the latter most 

 probably being in the form of a syncytium. Later this syncytium 

 differentiates fibres, the neuroglia fibres, which, according to Weigert 

 and others, may be entirely separate from the cells (Fig. 91), but 

 more probal)ly lie wholly or at least partly within them. In the 

 syncytium there are also to be distinguished an endoplasm of granular 

 protoplasm and a clear ectoplasm which may perhaps be regarded 

 as a matrix. (See also Fig. 321.) The structure of neuroglia would 

 thus be analogous to that of fibrous connective tissue, i.e., composed 



Fig. 91.— Neuroglia Cells and Fibres from the White Matter of the Human Cere- 

 bellum stained by Weigert's neuroglia stain. A, NeurogUa cell; B, blood-vessel cut 

 longitudinally, and C, blood-vessel cut transversely, showing enveloping neuroglia 

 fibres; a, neurogUa fibres; b, cytoplasm of neurogUa cell. (Cajal.) 



of cells, the neuroglia cells, a fibrillar substance, the neuroglia fibres, 

 and a ground substance. The Golgi method apparently reveals a 

 great variety of neuroglia cells which may be divided into cells with 

 straight radiating unbranched processes, spider cells, and rough 

 thick branching cells, mossy cells. It seems probable that in the 

 former both cells and fibres are stained while in the latter only por- 

 tions of the cells or syncytium, this method not differentiating 

 between cells and fibres. 



An increased activity of the neuroglia, due it may be to some 

 pathological cause, is indicated by increase in the endoplasm, by 

 proliferation of the nuclei, and by some cells detaching themselves 



