Figure 1.

Whole-mount in situ hybridization of early midbrain-hindbrain junction markers in wild-type and Pax-2 −/− e9.5 mouse embryos. None of the markers shows alteration in the mutant as compared with the wild type. The white dotted line in A, B, G, and H, and the arrowhead in E mark the isthmic constriction. The black line in G follows the ventral side of the forebrain and midbrain. CB, cerebellum; FB, forebrain; mab, mandibular part of the first branchial arch; MB, midbrain; mhj, midbrain-hindbrain junction; VIIIv, otic vesicle; lam, lamina terminalis.