Cyclopamine affects cell differentiation in the regenerating tail. (A-C) Histological analysis of the regenerating tail at day 3. Sagittal sections were stained with hematoxylin and eosin. Cyclopamine suppressed the elongation and the vacuolation of the regenerating notochord cells. It also suppressed the formation of the neural ampulla (C). nc, notochord. na, neural ampulla. sc, spinal cord. Bar, 200 μm. (D-I) Immunohistochemical detection of nerve cells and myofibers in the regenerating tail at day 5. Whole mount sample was immunostained with an anti-NCAM monoclonal antibody (4d) and a monoclonal antibody 12/101 to detect the nerve cells (D-F) and the myofibers (G-I), respectively. Arrows indicate the regenerated spinal cord (D-F) and the regenerated myofibers (G, H). Bar, 500 μm. (J-K) Immunofluorescent detection of muscle cells. The frontal cryosection was immunostained with a monoclonal antibody 12/101 (J, K) or an anti-PAX7 monoclonal antibody (L, M) to detect myofibers (white arrows in J, K) or myoblasts (white arrows in L, M) in the regenerated tail at day 5. Bar, 200 μm. A pair of black and white arrowheads marks the amputation plane.