Extended mucus removal time attenuates immunofluorescent labeling. (A-D) Planarians labeled with mAb 3F11 after HCl (A-B) or NAc (C-D) treatment for the times indicated. (E-H) Planarians labeled with mAb 2D2. (I-L) Planarians labeled with mAb 2C11. Planarians were relaxed in magnesium chloride, treated with 2% HCl or 7.5% NAc, fixed in formaldehyde, and bleached in 6% H2O2/PBS (3F11) or 6% H2O2/MeOH (others) (12-16 hr). Magenta arrows indicate reduced labeling. Yellow arrow (L) indicates increased labeling of pharynx. Scale bars: 500 μm.