
Fig. 5. Expression patterns of Shh (A-D) and Ptc (E-H) on serial sections at E3. (A,E) control level of expression; (B,F) midline cell-deprived neural tube level; (C,G) SHH-producing cell grafted level (experiment A3); (D,H) midline cell-deprived neural tube grafted on a layer of SHH-producing cells in a host (experiment B3). Ptc is upregulated (arrowheads) in the presence of SHH; Shh, SHH-producing cells.