Figure 4

Mapping of cad7 and cad20 expression on progenitor domains in the hindbrain. A-D: Expression analysis on the dissected whole brain (A, C) and cross-sections at r7 (B) and r6 level (D) of E11.5 embryo. Images of A and C are taken from the lateral side of the brain. At E11.5, cad7 mRNA is mainly detected in the dorsal domain of the neural tube posterior to r5/6 boundary (arrow in A), and the ventral border of cad7 corresponds to the dorsal border of Dbx2 (arrowhead in B, cross-section at r7 level after double detection). At E11.5, cad20 transcripts are highly detected in the middle domain of the hindbrain anterior to r6/7 boundary (arrow in C), and the dorsal area of cad20-domain overlaps with the ventral area of Gsh1-domain (arrowhead in D, cross-section at r6 level after double detection). E-J: Expression analysis on the dissected whole brain (E, I) and serial cross-sections at r7 level (F-H, and J) from E12.5 embryo. Images of E and I are taken from the lateral side of the brain. The ventral border of cad7 in the dorsal progenitor domain is consistent with the dorsal border of Dbx2 (arrowheads in F and G), and part of cad7-expressing progenitors gives rise to Lbx1-positive dorsal interneurons (Dl4-6) (H). The expression of cad20 in the middle domain of the hindbrain gradually disappears at E12.5 (I), and another expression domain of cad20 also appears in a more ventral region (arrow in I and J). K-L: BrdU detection after in situ hybridization. The domain of cad20-expressing cells corresponds to that of cells expressing Gata2, a V2 interneuron lineage maker (brackets in K and L), and cad20 expressing cells are progenitor cells incorporating BrdU (arrow in L). M-N: Summary of expression of cad7 and cad20 along D-V axis at E11.5 (M) and E12.5 (N). Left: expression domains at r5 and r7. Right: progenitor domains defined with expressions of homeodomain transcription factors and cadherins. Broken lines indicate the border between basal and alar plates. V0–V2, V0–V2 interneuron; SM, somatic motor neuron, BM, branchial motor neuron. Scale bars: 500 μm in A, C, E and I; 150 μm in B, D; 200 μm in F, G, H and J; 200 μm in K, L.