Fig. 2. Characterization of mespb-knockin mice. (A) Intercrossing of heterozygous mespb/+ mice gives rise to viable mespb/mespb mice with kinked tails. In these mespb/mespb (C) and neo-mespb/neo-mespb (D) embryos, the mespb genes introduced are expressed in the expected region, which are similar to that of Mesp2 (B). Segmented somites are observed in both mespb/mespb (C) and neo-mespb/neo-mespb embryos, but not in Mesp2–/– embryos (E). However, the skeletal morphology (F-I) showed various defects in vertebrae formation in both mespb/mespb (G) and neo-mespb/neo-mespb (H) embryos. Embryo samples were prepared at 11.5 dpc. Skeletal specimens were prepared at 18.5 dpc. Anterior is to the left. Genotypes for various mice are schematically represented on the left. Mesp2, endogenous allele; neo, pgk-neo cassette replaced with Mesp2 for gene targeting (ref); mespb, zebrafish mespb gene; gray arrowhead, lox sequence; pA, polyadenylation signal.
