NEUROGLIA 465 



The astrocytes (Belter's cells), when stained by the Golgi 

 method, apparently consist of a small cell body and an innumera- 

 ble number of long slender processes. 

 Two varieties of these cells are recog- 

 nized; the spider cell or long-rayed 

 astrocyte, with a small cell body and 

 very many exceptionally long and slen- 

 der processes; and the mossy cells or 

 short-rayed astrocytes, whose processes 

 are shorter and somewhat thicker but 

 decidedly more varicose than those of 



the long-rayed tvpe. Fi- 368. A SHORT-RAYED ASTRO- 



Recent investigations by means of OYTE ' OB MOSSY CELU 



the staining methods of Weigert, Mai- Golgi ' s 



lory, and Benda, have demonstrated 



that the astrocytes, as seen in the Golgi preparations, probably in- 



clude two distinct structures, the glia cells and the glia fibres. 



Olia cells, as seen in sections prepared according to these meth- 

 ods, appear as small cytoplasmic cells with large and deeply 

 staining nuclei. In the small glia cells the cytoplasm is so slight 

 as to form scarcely more than a mere rim about the nucleus ; in 

 the larger cells the cytoplasm is more abundant and the processes 

 larger and more numerous. The presence of cytoplasmic proc- 

 esses gives the cell an irregularly stellate appearance. In Golgi 

 preparations these processes can not be distinguished from the 

 dense network of glia fibres with which they are surrounded. 



The glia fibres comprise numerous filiform fibrils which occur 

 as a dense network around the glia cells, from which they radiate 

 in all directions. They pass alongside of, over, or under the glia 

 cells ; their filaments have even been described as passing entirely 

 through the cytoplasm of the cell. Nevertheless they appear at 

 all points to be anatomically distinct from the cell body. 



The relation of the glia cells to the fibres of neuroglia is perhaps 

 comparable to the arrangement in fibrous or reticular tissue. The 

 fibres of each of these tissues appear to be ontogenetically derived 

 either directly or indirectly from its cells, yet when fully formed 

 they often exist as anatomically distinct elements. 



Neuroglia cells and fibres occur in both the grey and white 



matter of the central nervous system, though perhaps more abun- 



dant in the latter. The fibres radiate for considerable distances 



from their glia cells, and thus form a supporting tissue for the 



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