document: Histopathological studies. Histopathological studies were performed on 10-µm sections of paraformaldehyde-fixed, paraffin-embedded mouse brains. Slides were soaked in hydrochloric acid–potassium ferrocyanide solution for 30 min at room temperature. The distribution of delivered b-3WJsiEGFR Let-7g conjugated with DFHBI-1T (green fluorescence) was monitored through ﬂuorescence microscopy imaging after staining nuclei with DAPI. The images were taken after 0.5, 1, and 2 h of CED infusion. For brain