
FITC (fluorescein isothiocyanate) refers to the fluorochrome used to label the monoclonal antibodies targeted against the cell wall antigens of both Giardia and Cryptosporidium. FITC fluoresces a brilliant apple green color. The color produced by FITC is superimposed on the wall of the cyst/oocyst.
DAPI (4’,6-diamidino-2-phenylindole) is a nucleic acid stain. It fluoresces blue and can show the position and number of nuclei present in the cyst/oocyst. The absence of DAPI stained nuclei may mean nuclei are absent or nuclei are present but the stain did not come in contact with the nuclei, possibly due to stain exclusion by the cell wall.
DIC (differential interference contrast) microscopy approximates a 3-D view of the object using polarized light which allows the microscopist to view the internal morphology or structure and note any unusual characteristics.

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