Fig. 2

Fig. 2 Expression of the periostin gene during embryogenesis. Wild-type embryos were hybridized with the periostin (A, B, D–I, and K–P) or myoD (C, J, and L) probe and fss embryos, with the periostin probe (H). The orientation is anterior at the top (A–E) and anterior at the left (F–H and K–P). No periostin expression is detected at the bud stage (A), and the segmented expression of periostin (B, D, and E) or myoD (C) is observed from the dorsal view of the 8-somite (B and C) and 16-somite stages (E) and from the lateral view of the 16-somite stage (D). A transverse section (I) and a sagittal section (K) show the expression of periostin in the lateral (I) and rostral (K) parts of segmented somites; and another transverse section shows myoD expression in the lateral and adaxial parts (arrows, see also I) of the somites (J). In flat preparation of 10-somite embryos (L), double labeling with periostin (purple, arrowheads) and myoD (red) shows their expressions, which lined one after the other in newly formed (posterior) somites but ambiguously in already formed (anterior) somites. In the lateral view of the 20-somite (F) or 26-hpf (G) stage, widely spread expression of periostin is observed. In fss embryos, no metameric pattern is observed in the trunk region (H). Horizontal (M and N) and sagittal (O and P) sections of 36-hpf embryos show that periostin expression is restricted to the small triangular regions that are surrounded by adjacent somites and notochord or spinal cord (N and P). Abbreviations: NC, notochord; S, somite; SC, spinal cord. Scale bars: A–H, 100 μm; I–P, 25 μm.