534 MYELIN STAINS 



washed in many changes of tap-water, dehydrated and mounted 

 in Gurr's neutral medium. Stewart recommends ringing the 

 coverslips with Kronig's Deckglaskitt to prevent crystalhsation 

 of the mounting medium. (This may be prepared by gradually 

 adding 8 parts of collophonium resin to 2 parts of melted paraffin 

 wax of melting point 54° C, mixing thoroughly and allowing to 

 cool.) 



1081. Other Methods for demonstrating Degenerated Myelin. 



LoRRAiN Smith and Mair {Journ. Path, and Bad., xiii, 1909, 

 p. 14) found that tissue which had been kept for an excessive 

 length of time in strong chrome solutions gave, when treated 

 by Weigert's myelin stain, the same picture as by the Marchi 

 process, i.e., only the degenerated myelin stained. They kept 

 frozen sections for varying times up to twenty-four days at 

 37° C. in a saturated solution of pot. bichromate, later staining 

 them with Kultschitzky's haematoxylin and differentiating with 

 borax-ferricyanide. 



Later (Journ. Path, and Bad., xxiv, 1921, p. 364 ; xxv, 1922, 

 pp. 143—403) they found that they could over-mordant sections 

 in the same way with various aldehydes, and even with formal- 

 dehyde if it contained paraformaldehyde. 



Hurst [Brain, xlviii, 1925, p. 1) applied a similar method to 

 the study of degenerating lipoids, mordanting frozen sections in 

 Weigert's fluorchrome-bichromate mordant at 37° C. for varying 

 periods from two to six days, and thereafter staining (one hour 

 at 50° C.) and differentiating as Wolters. He found that myelin 

 stains best after one or two days' mordanting and fatty acids after 

 two or three days, whereas after four to six days' mordanting only 

 neutral fat was stained. 



LoRRAiN Smith (J. Path, and Bad., xi, 1906, p. 415) stained 

 fats in frozen sections with a mixture of basic anilin dyes and 

 sulphurous acid. This method depends on the conversion of 

 neutral fats to fatty acids which combine with the dye. R. C. J. 

 Stewart [Journ. Path, and Bad., xliii, 1936, p. 339) has success- 

 fully used the following modification : frozen sections of formalin 

 fixed tissues are washed in tap-water for five minutes and placed 

 in equal parts of 2 per cent, oxalic acid and 2 per cent, potassium 

 sulphite for two to three minutes. They are then stained in 

 0-025 per cent, methylen blue for one hour and subsequently 

 returned to the above bath for differentiation which should be 

 controlled under the microscope ; this is usually complete in six 

 or seven minutes. The sections are again washed in tap-water, 

 placed in 5 to 10 per cent, acid ammonium molybdate solution 

 for three or four minutes and then transferred to a solution of 

 equal parts of glycerin and saturated ammonium picrate in 

 distilled water. They are mounted in glycerin jelly to which a 

 little ammonium picrate has been added. 



