MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



FIELD'S STAIN 

 For thick blood films for malaria parasites 



Solutions required: 



A. Field's stain, A 



B. Field's stain, B 



Technique: 



1. A thick film is made by spreading two or three drops of blood 

 into a circle of about 2 cm. diameter on a slide. 



2. Allow to dry in the air until the films are no longer obviously 

 moist. 



3. Immerse the film for one second in Field's stain A ; then im- 

 mediately transfer to a dish of distilled water and wave the slide 

 gently in the water until no more stain comes away and the slide 

 is free of excess stain. 



4. Immerse the film for one second in Field's stain B; then 

 rinse by waving gently for two or three seconds in a dish of fresh 

 distilled water. 



5. The films should be placed in a vertical position and left to 

 drain and dry in air. 



Notes: 



Freshly prepared films give the best results. 



Staining times may be varied from one to five seconds. 



Results: 



General ground: creamy yellow, sometimes uniform, sometimes 

 mottled with pale blue. 



Leucocytes: — Nuclei, deep blue, sharply defined. Cytoplasm 

 pale blue, vaguely defined. Granules, eosinophilic, large, dull 

 red, well defined. Neutrophilic, small, pale purple, vague. 



Malaria parasites : Cytoplasm, blue. Chromatin, dark, purplish 

 red. Pigment, unstained yellow of varying shades depending on 

 the depth of the cytoplasm in which it lies. 



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