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Description:This 1981 photograph depicted the materials used in a laboratory setting in order to carry out the trichrome staining method during the preparation of a wet fecal mount.

Trichrome Staining Procedure

It is generally recognized that stained fecal films are the single most productive means of stool examination for intestinal protozoa. The permanent stained smear facilitates detection and identification of cysts and trophozoites and affords a permanent record of the protozoa encountered. Small protozoa, missed by wet mount examinations (of either unconcentrated or concentrated samples) are often seen on the stained smear. The Wheatley Trichrome technique for fecal specimens is a modification of Gomori’s original staining procedure for tissue. It is a rapid, simple procedure, which produces uniformly well-stained smears of the intestinal protozoa, human cells, yeast, and artifact material.

The specimens usually consist of fresh stool or stool fixed in polyvinyl alcohol (PVA) smeared on microscope slides and allowed to air dry or dry on a slide warmer at 60°C. Stool preserved in sodium acetate-acetic acid-formalin (SAF) or some of the one-vial fixatives can also be used.


There are seven steps to this procedure, requiring the following solutions:

1.- 70% Ethanol plus iodine: prepare a stock solution by adding iodine crystals to 70% alcohol until you obtain a dark solution. To use, dilute the stock with 70% alcohol until a dark reddish brown color or strong tea color is obtained

2.- 70% Ethanol (twice)

3.- Trichrome Stain: may be purchased commercially

4.- 90% Acid Ethanol

    - 90% ethanol = 99.5 ml

    - Acetic acid (glacial) = 0.5 ml

5.- 95% ethanol

6.- 100% ethanol (twice)

7.- Xylene or xylene substitute (twice)

High Resolution: Click here for hi-resolution image (4.89 MB)
Content Providers(s):CDC/ Dr. Mae Melvin
Creation Date:1981
Photo Credit:
Links:CDC – Div. of Parasitic Diseases, DPDx; Stool Specimens: Staining Procedures
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Copyright Restrictions:None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.