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Table 2 Outline of stains used in histopathological evaluation

From: Histopathological evaluation of ocular microsporidiosis by different stains

S.No Stain Morphological features Remarks
1 Hematoxylin and Eosin pale pink, ill-defined morphology Most common tissue stain, should raise the suspicion of microsporidia. Appearance may resemble yeasts, needs confirmation by other stains
2 PAS pink to purple in colour, ill defined morphology Poorly stained, but the pink dot at the pole could suggest microsporidia. Not confirmatory
3 Giemsa stain not taken up be cell wall, appears blue, Stains the organism blue, but does not stand out against the blue background with also shows granular debris Easy to perform
4 GMS oval to round, brown in colour, internal band is easily spotted, background green Good stain, highlights the organism again the background under low magnification. Expensive reagents, time consuming
5 CFW blue, oval, diffusely fluorescing spores, sometimes only spore wall fluoresced Easy for experienced observer, but can be confused for yeasts. Produces high background noise
Cannot be done without a fluorescence microscope
6 Acridine orange oval, refractile, yellowish-green to orange fluorescence, no demarcation from the background Easy for experienced observer, but can be confused for yeasts. Produces high background noise
Cannot be done without a fluorescence microscope
7 Gram gram variable, waist band visible, poor contrast from background, plenty of inflammatory debris Economical, easy to perform. Variable staining, high background noise is a limitation. Microbiologists find it familiar and easy to extrapolate with cytologic findings
8 Masson's Trichrome spores appeared red against a blue background, ill-defined internal morphology High background noise, difficult to standardize the stain. Pathologists familiarity more than microbiologists
9 1% acid fast oval, bright red with a darkly stained belt across the spore, visible against a blue background Good contrast, easy interpretation, less time and economical. Unstained forms can also be found
10 Gram's chromotrope spores appear purple to pink against green background, characteristic belt visible Provides good contrast, easy to detect the organism under lower magnification. Has the added advantage of Grams and Massons trichrome, less time