STAINING, PRACTICAL AND THEORETICAL 



B. Unna's polychrome methylene blue. 



This should be diluted i : lo or i 115 for use. 



1. Fix tissues (any fixative may be employed); dehydrate; 

 clear; and embed. 



2. Paraffin sections are brought down to 70% alcohol in the 

 usual manner; flood with freshly filtered orcein solution, pre- 

 pared as above, and warm gently for ten to fifteen minutes, until 

 the solution thickens. Alternatively, the sections may be stained 

 overnight at room temperature. 



3. Wash thoroughly with 70% alcohol. 



4. Wash thoroughly with distilled water. 



5. Stain in diluted polychrome methylene blue until the nuclei 

 are bright blue to blue-black; the time necessary may be ascer- 

 tained by examining under the microscope at intervals. 



6. Differentiate in 95% alcohol, followed by absolute. 



7. Clear in xylol and mount. 



Results: 



Elastic fibres : deep brown. Nuclei : bright blue or blue to black. 

 Connective tissue: pale brown. 



Note: If it is desired only to stain the elastic fibres, omit No. 5, 

 and treat sections with acid alcohol for a few seconds before 

 washing with distilled water. 



References : 



Mallory, F. B. (1938), p. 171. 

 Unna, P. G. (1891). 



