SECTION TWO 



DOPA REAGENT 

 For melanoblasts 



Solutions required: 



Dopa reagent (3 :4-dihydroxy- 



phenylalanin) . . . . 0-2 gm. 



Cold distilled water . . . . 200 ml. 



Note: This solution, which deteriorates fairly 

 rapidly at normal temperatures, should be kept in a 

 refrigerator. When the solution turns dark red it is 

 useless and should be discarded. 



B. Buffer tablet pH 7-4 

 Distilled water (cold) 



C. Solution A 

 Solution B 



I tablet 

 100 ml. 



25 ml. 

 8 ml. 



Note: This solution must be freshly prepared as 

 required. 



Technique: 



Tissues should be fixed not longer than two to three hours in 

 5% formalin, or frozen sections of fresh material may be employed. 



1. Rinse with distilled water from four to five seconds; then 

 immerse in Solution C for three to four hours, controlling under 

 the microscope at intervals, until melanoblasts are stained black. 



Note: This solution is likely to overstain if it becomes sepia 

 brown. 



2. Wash with distilled water; dehydrate; clear; mount 



Result: 



Melanoblasts: black. 



Notes: 



{a) After dehydration (in stage 2) 1% crystal violet in absolute 

 alcohol may be employed as a counterstain, if desired. 



{h) " Dopa " is an abbreviation for dihydroxyphenylalanin. 



Reference: Laidlaw, G. F. (1932). 



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