STAINING, PRACTICAL AND THEORETICAL 



32. Clear in xylol. 



33. Mount in neutral Canada balsam in xylol, or in D.P.X., 

 Clearmount, or Cristalite. 



Results: 



Reticulum: black. Elastin: red. Collagen: blue. Colloid: 

 brown or grey. Nuclei: brownish black. Erythrocytes: light 

 orange. Smooth muscle: light buff. Striated muscle: greyish blue 

 or mauve. Epithelium: light greyish brown. Cellular debris: 

 light greyish brown. 



Notes: 



(a) The technique is a modification of the Lewis & Jones (1951) 

 recommended staining procedure for diagnosis of invading 

 carcinomas, diseases of the cardiovascular system, tuberculosis 

 and other inflammatory reactions. 



(b) The authors (Humason & Lushbaugh) claim that their 

 modification, described above, has resulted in better defined and 

 more easily interpreted stain for the three connective tissue 

 components; that there is less background colour than in the 

 original method and sections, even as thick as 20 to 25^11 show 

 clear detail and exhibit a three-dimensional effect. 



(c) Periodic acid oxidation is used in this technique in place of 

 potassium permanganate, because the authors found the former 

 to be more selective in its action, thereby producing a superior 

 histological picture of connective tissue with even the smallest 

 fibres well defined. 



(d) In this technique the specific staining of collagen is streng- 

 thened by treatment of the sections with phosphomolybdic acid 

 before staining with aniline blue: this also reduces cytoplasmic 

 staining to a minimum. 



(e) To prevent the sections from becoming detached from the 

 slides during processing in the various solutions they were first 

 dried thoroughly on albuminized slides on a warming plate or in 

 an oven overnight, followed by fifteen minutes or more in a 

 mechanical hot-air dryer. If a mechanical dryer is not available, 

 the authors advise careful warming over a small flame until the 

 paraffin wax around the sections just begins to melt. It is recom- 

 mended that no attempt should be made to stain the sections on 

 the same day that they are mounted on the slides, 



362 



