Dopa Oxidase Reaction 351 



ately closed. Slides may l)c placed in fluid in (o\ered coplin jars ^\ith 

 nitrogen bubbling through. 



solutions: 

 Substrate: 



Stock buffered succinate; equal volumes of: 

 0.2M phosphate buffer, pH 7.6 

 0.2M sodium succinate 

 Incubating solution; equal volumes of: 

 buffered succinate 

 nitro BT (10 mg./lO ml. distilled ^vater) 



procedure: 



1. Place sections or slides in incubating solution, 37°C: 1-2 hours or 

 until sufficient color is preser.t. 



2. Wash in physiological saline: 1 minute. 



3. Fix in 10% forinalin: 1-24 hours. 



4. Mount loose sections in glycerol jelly, or mount on slides and pro- 

 ceed to step 5. 



5. Dehydrate, clear, and moimt. 



Sections may be counterstained in safranine or hematoxylin. 



results: 

 sites — blue 



References: Farber and Bueling (1956); Farber and Fouviere (1954); 

 Friede (1958); Nachlas et al. (1957); Novikoff et al. (1960); Pearson 

 (1958); Rosa and Velarde (1954); and Rutenburg et al. (1950, 1956) 



Dopa Oxidase Reaction 



The Dopa reaction is considered specific for melanoblasts and mye- 

 logenous leucocytes which are supposed to contain an intracellular fer- 

 ment, dopa-melanase. The latter converts the 3,4 dioxyphenylalanine 

 into a blackish brown pigment, the black condition of the reacting cell. 



Laidlaw's Method (click, 1949) 



fixation: only fresh tissue with no fixation (or 5% formalin for no 

 longer than 3 hours, but results are inferior to those from fresh tis- 

 sue). 



