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 |