OTC labeling in the cytosol of spfash/hOTC and spfash/mOTC hepatocytes. Ultrathin frozen liver sections from a spfash mouse treated with Ad.hOTC (A) and a spfash mouse treated with Ad.mOTC (B) were labeled by the rabbit anti-OTC antibody followed with gold conjugated goat anti-rabbit antisera. Arrows indicate OTC binding sites within the cytosol. ER, endoplasmic reticulum; N, nucleus. Bars, 0.1 µm.