This is an example of an immunofluorescence test positive for anti-microsomal antibody, one of the autoantibodies that can be seen with autoimmune diseases of the thyroid. A major component of the antimicrosomal antigen is thyroid peroxidase (TPO) which is often measured serologically. Note the bright green fluorescence in the thyroid epithelial cells, whereas the colloid in the center of the follicles is dark.

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