MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



2. A fresh mixture is prepared by diluting Giemsa stain in the 

 proportion of lo drops of stain to lo ml. distilled water. The slide 

 is then placed in a staining jar and left to stain in the diluted 

 Giemsa for sixteen to twenty-four hours ; if a staining jar is not 

 available, place a piece of thin glass rod in a Petri dish; lay the 

 slide with one end resting on the rod, film face downwards, in the 

 Petri dish, and pour in sufficient diluted stain to cover the film; 

 then line the Petri dish lid with two sheets of moist filter paper to 

 prevent evaporation, and cover the preparation. 



3. Wash with distilled water; blot and dry. 



Method for bacterial smears, throat exudate, etc. : 



1. Thin, air-dried, unfixed smears are covered with undiluted 

 Giemsa stain for thirty seconds ; then a quantity of distilled water, 

 equivalent to five to ten times the volume of stain used, is added 

 and mixed with the stain by gently rocking the slide. 



2. Allow the diluted stain to act for two to five minutes ; then 

 wash with distilled water; blot and dry. 



Thin blood film method : 



1. Air-dried films are fixed for five minutes in pure methyl 

 alcohol ; then blotted and dried in air. 



2. Stain for fifteen to forty-five minutes in a mixture consisting 

 of one part of Giemsa stain and twenty-five parts of distilled water. 



3. Wash in distilled water; blot and dry in air. 



Results: 



Nuclei of the leucocytes are stained reddish purple, while the 

 rest of the leucocytes appear similar to Leishman-stained prepar- 

 ations. Cytoplasm of plasmodia, blue. Chromatin, red. 



Thick film method (for demonstrating malaria parasites) .* 



1. A film is prepared by spreading 3 to 5 drops of blood in a 

 circle about 15 mm. diameter over a slide; then without fixation 

 it is allowed to dry on a level surface for eighteen to twenty-four 

 hours at room temperature protected from dust ; or for two to three 

 hours in an incubator at 37° C. 



2. Stain for forty minutes in a mixture consisting of one part of 

 Giemsa stain and fifty parts of distilled water. 



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