Figure 4. BMP signaling affects roof-plate specification, but not overall dorsal cell-fate specification.
(A, B) Dorsal EGFP (A) and Noggin (B) electroporations demonstrating reduced WNT1 expression in the Noggin-electroporated roof plate (RP), although the ventral limit of GLI3 expression is unaltered. Note the presence of a cyst/rosette at the top left of Fig. 4B. (C–F) Dorsal EGFP (C) and caBMPR1 (D) electroporations demonstrating increased WNT1 expression in D, F, while PAX7 expression remains unaltered (E, F). Arrowheads in D mark the ectopic expression of WNT1 outside the roof plate (RP), while arrowheads in E and F mark the lateral edges of the RP in control (E) and BMP4 (F) electroporated dorsal midbrains.