Fig. 1

A somite-like physical boundary is formed at the edge of the Tbx6-expressing cell mass.

a Schematic illustration of Tbx6, ripply1 and ripply2 expression during zebrafish somitogenesis. b Schematic representation of somite boundary structure in wild-type (left) and tbx6 or ripply1/2 double-deficient embryos (right). In wild-type embryos, fibronectin is assembled at the somite boundary. In addition, cells adjacent to somite boundaries are epithelialized with accumulation of F-Actin at the basal domain²⁵. c Schematic representation of transplantation experiment. Rhodamine/Biotin-labeled cells from tbx6-or ripply1/2 double-deficient embryos were transplanted to the lateral margin of the tbx6 deficient host embryo at the dome-40% epiboly stage. Chimeric embryos were fixed at somite stages 8–9 and flat-mounted after IHC staining. The green box indicates the approximate area observed in (d, e) and Supplementary Fig.  2. d, e IHC staining of fibronectin (green) and Tbx6 (blue) in tbx6-deficient embryos with transplanted tbx6-deficient donor cells(d; n = 16) and ripply1/2 double-deficient donor cells (e; n = 17). Donor cells were detected with rhodamine labeled streptavidin (red). (d’,d”,e’,e”) High-magnification images of the area indicated by yellow boxes in (d) and (e). Aligned nuclei are indicated by white arrow-heads in (e”). Scale bar indicates 50 µm in (d).