CHAPTER XLIII 

 NEUROGLIA AND SENSE ORGANS 



NEUROGLIA * 



1082. Introduction. Neuroglia cells may be isolated by teasing 

 after maceration in weak solutions of potassium bichromate or 

 33 per cent, alcohol, and then stained, preferably by means of 

 dilute picrocarmine or other carmine solutions. They may be 

 studied, also., in sections made from non-imbedded material fixed 

 in solutions of chromic salts and stained with carmine, nigrosin, 

 orcein and so on. Sections made from either fresh material 

 hardened by the ether freezing method and treated with a weak 

 solution of osmic acid (§ 40), or from tissues hardened in 

 potassium bichromate, can be advantageously stained with watery 

 solutions of anilin-blue-black or nigrosin. Also, sections cut from 

 material fixed, hardened and imbedded by the usual methods 

 may, up to a point, be employed for getting a general, though 

 incomplete, view of the amount and arrangement of the neuroglia 

 in a given nervous organ. Iron haematoxylin, particularly after 

 fixation in corrosive sublimate or other fluids containing it, gives 

 good results with sections of central nervous organs of lower 

 vertebrates, chiefly of fishes. 



See GoLGi, Opera Omnia, i, pp. 1 and 3 to 70 ; ii, p. 461 ; Ranvier, 

 Traite, etc. ; Bevan Lewis, " The Human Brain " ; E. Muller, Arch, 

 mikr. Anat., Iv, 1900, p. 11 ; Studnicka, Anat. Hefte, xv, 1900, p. 316, 

 and the literature quoted therein. 



But the best method for the study of morphology and relation- 

 ship of ependyma cells and astrocytes has been for many years, 

 and in a sense still is, Golgi's rapid process (§ 1028), the best 

 material being that which has been placed for about two or three 

 days in the osmio-bichromic mixture. 



This method, however, does not allow of any tinctorial differ- 

 entiation, either between neuroglia cells and nerve-cells, or 

 between neuroglia cells and neuroglia fibres. One might even say 

 that it is unsuitable for the demonstration of the latter, the 

 existence of which was clearly established only after the publica- 

 tion of Weigert's method (see next §), the first and, perhaps even 

 now, most important of all so-called specific processes for staining 

 neuroglia fibres. 



* J. G. G. and R. O. S. 



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