FITC-labeled SiO2-NP (55 ± 6 nm in diameter) within a single SiO2-containing cell of the subcutaneous tissue visualized by conventional widefield (a) versus superresolution structured illumination microscopy (b). Red circles indicate nuclei, white outlines indicate outer cell borders. FFPE subcutaneous tissue sections from mice following subcutanous injection of FITC-labeled SiO2-NP were sliced and dewaxed according to standard protocols. The dewaxed, unstained slides were covered and observed with the ELYRA inverted microscope (Carl Zeiss, Jena, Germany). The comparison of the conventional wide field image (a) and superresolution structured illumination image (b) yields a clearer and less blurry image of clustered FITC-labeled SiO2-NP.