DS 21.21 DS 21.211 DYE STAINS OF SPECIAL APrLICATION 401 



21.21 NERVE CELLS AND PROCESSES 



Nerve cells and processes are stained more easily by the dye-staining techniques, than 

 they are by metal-staining techniques. It must be admitted that most of the techniques 

 are not so specific, but they are certainly adequate for class demonstrations; and it must 

 not be forgotten that much of the classical research was done by these methods rather 

 than l)y metal stains. These techniques can be divided into three groups: first, the 

 thiazin (methylene blue and toluidine l)lue) methods (DS 21.211) whioli were among the 

 first to be employed; second, the great division of hematoxylin stains (DS 21.212) with 

 which the name Weigert is linked; third, other dye-staining methods (DS 21.213) which 

 have from time to time occurred in the literature. 



21.211 Methylene Blue and Toluidine Blue Methods 



The thiazin nerve-staining techniques, once far more numerous and of wider employ- 

 ment than is today the case, can be broadly divided into two divisions : those which are 

 customarily applied to sections of fixed material, and those which are applied to living 

 tissues for subsequent fixation. In the latter case, some phosphomolybdate or picrate 

 salt is applied to precipitate the blue stain which has been differentially absorbed into 

 the nerve cells. Both methods depend for their success on accurate timing, for if the 

 stain is permitted to act too long, other tissues than nerves become deeply stained ; if too 

 short a time is allowed for their absorption, a most disappointing result will be obtained. 

 The classic technique for injection into the Uving animal is that of Bethe 1896, who 

 published in the journal cited below no less than five separate formulas for materials 

 designed to fix the blue in the Jiving tissues. It is still a^method which should not be 

 ignored, since successful preparations are certainly as good as those to be obtained by 

 the metal-staining techniques. The second type of technique for living materials is that 

 of Cajal 1893, now practically forgotten, in which solid methylene blue is sprinkled upon 

 a freshly cut surface of brain and allowed to absorb for such time as is considered 

 necessary. The stain is very capricious, but the results obtained when it is used suc- 

 cessfully are of great beauty. The technique of Betsa 1910, though slow, is one of the 

 surest methods by which a good demonstration of Purkinje cells may be provided for 

 class-teaching purposes. 



21.211 Alzheimer 1910 Nissl and Alzheimer 1910, 409 



REAGENTS REQUIRED*. A. ADS 12.1 Weigert 1891; B. sat. aq. sol. phosphomolybdic acid; 



C. DS 13.7 Alzheimer 1910 

 method: [10 M sections by freezing technique] -^ water — > .4, 6 hrs. -* wash -^ B, 2-12 



hrs. -^ rinse -^ C, till sufficiently stained -^ wash -^ balsam, via usual reagents 



21.211 Bacsich 1937 11025, 72:163 



REAGENTS REQUIRED: A. ADS 12.1 Bacsich 1937; B. DS 11.124 Bacsich 1937; C. abs. 



ale. 50, ether 50 

 method: [celloidin sections of formol material, attached to slide with V 21.1 Mayer 1884 



and varnished with celloidin] -* water -^ A, 2 hrs. 36°C. -^ thorough wash -^ B, 2 



lirs. 37°C. -^ thorough wash -» 95% ale, till dehydrated -* C, to remove varnish -^ 



balsam, via usual reagents 



21.211 Besta 1910 766, 36:477 



REAGENTS REQUIRED: .4. 0.1% thionin; B. 20% creosote in 95% ale; C. creosote 

 method: [sections of F 0000.1200 Besta 1910 fixed material] -> water -> A, 2-3 hrs. -^ 



B, until differentiated —* C, till clear -» balsam, via xylene 

 note: This method was originally recommended for the demonstration of Purkinje cells 



but is of wider application. 



21.211 Bethe 1896 766, 12:438 



REAGENTS REQUIRED: A. sat. sol. {circ. 4.5%) methylene blue; B. sat. sol. (arc. 1.2%); 



ammonium picrate; C. water 100, sodium phosphomolybdate 5, osmic acid 0.25, 

 hydrochloric acid 0.2 



