Fig. 6. Gene expression implicated in the segmental border formation. The expressions of Lfng (A-F) EphA4 (G-L) and PAPC (M-R) are compared in various mespb embryos at 11.5 dpc. Lfng is expressed in a highly dynamic manner. Therefore, 8-10 embryos of each genotype were analyzed by whole-mount in situ hybridization and we chose those with similar expression patterns for the comparison. The anterior thinner band of Lfng (black arrowhead) is rostrally extended in the Mesp2-null embryo. In contrast, the sharpness of the band was recovered in all mespb embryos. The rostral band of EphA4 (green arrowhead) and PAPC (purple arrowhead) expression, which disappeared in the Mesp2-null embryo, is also present in mespb embryos.