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Fig. 4. Ependymal cells and tail blastema cells express the hedgehog receptor
Ptc1. (A-F) In situ hybridization of Ptc1 on cross-sections.
Sense probe shows no staining of the entire cross-section both in control (A)
and agonist-treated (D) regenerates. Ptc1 is expressed in the ventral
ependymal cells (dashed line marks the ependymal tube) and in the blastema,
but not in the epidermis (B,C). Note that the staining in the blastema is
strongest in the cells surrounding the ventral spinal cord. C is taken at
twice the magnification of B. A-C is 4 dpa. Ptc1 expression is
increased in agonist-treated regenerates (E,F). Now all the ependymal cells
express Ptc1 and the vast majority of ventral blastema cells do
(compare ventral to dorsal blastema cells). F is taken at twice the
magnification of E. D-F is 5 dpa. Scale bars: 100 µm.