278 Cytoplasmic Elements (chap. 18) 



comments: 



Staining with chrysoidin can be preceded with hematoxylin or PAS. 

 The author likes this method. 



Metachromasia 



A certain few tissue elements are stainable by a particular group of 

 cationic dyes, changing in the tissues from blue (the usual orthochro- 

 matic form) to a purplish-red or reddish-purple hue. Such a dye, called 

 metachromatic (see page 110), is of considerable value in the study of 

 specific elements of connective tissue. Among the metachromatic dyes 

 most commonly used are toluidine blue O, thionin, methylene blue, 

 azures, crystal violet, cresyl violet, methyl violet, safranin O, celestin 

 blue, gallocyanin, and pinacyanol. Some of the tissues identified by this 

 means are mast cells, amyloid, cartilage, and mucus materials [Schubert 

 and Hamerman, 1936). 



The methods are tricky and a technician must learn to distinguish a 

 true metachromasia from a false one. The difficulty in preserving meta- 

 chromasia lies in the dehydration of the tissue after staining. Increasing 

 strengths of alcohol (ethyl) revert the dye back to the orthochromatic 

 form. Sections can be examined in an aqueous condition, but this 

 produces at best a semipermanent preparation. Some workers use 

 acetone or tertiary butyl alcohol for dehydration, then follow with one 

 of the clearing agents. Padawer (19'>9) uses Ether 181 (page 282) and 

 Levine (1928) used oil of cloves for dehydration (page 281). 



Amyloid * 



Crystal Violet (lieb, 1947) 



fixation: 10% formalin or alcoholic fixative. 



solution: 



Crystal violet stock solution: 



crystal violet, C.I. 42555 (14.0-15.0 gm.); satu- 

 rated in 95% ethyl alcohol 100.0 ml. 



Working solution: 



stock solution 10.0 ml. 



distilled water 300.0 ml. 



hydrochloric acid, concentrated 1.0 ml. 



' See Amyloid Staining, page 274. 



e I 



