Fig. 5. Alterations of specific motor pools in Raldh2^L–/– brachial LMC at E12.5. (A-D) Ephb2 transcripts on flat-mounted spinal cords (A,B) and transverse sections (C,D) at levels indicated in A,B. (E-H) Epha4 transcripts on flat-mounted spinal cords (E,F) and transverse sections (G,H) at levels indicated in E,F. Brackets (E,F) indicate the extent of the Epha4 motor pools along the AP axis. The asterisk (H) points to decreased Epha4 signal in the Raldh2^L–/– lateral LMC. (I-L) Pea3 transcripts on flat-mounted spinal cords (I,J) and transverse sections (K,L) at levels indicated in I,J. Horizontal bars (white in J and red in K,L) delineate the larger distance between the ventral midline (dotted lines, I,J) and the Pea3+ cells in mutants. Raldh2 immunofluorescence has been combined with in-situ hybridization on control spinal cords (A,E,I, green), the overlay of the two signals is shown on the left side only. (M,N) Gdnf transcripts on transverse sections at thoracic and brachial plexus (bp; insets) levels. (O,P) X-gal staining of RARE_hsp68_lacZ transgenic embryos. (P) The red arrowhead points to the almost complete absence of staining in the cutaneous maximus (CM) hypaxial muscle.