Fig. 1. Xena localization during somitogenesis. (A) At stage 17, Xena is enriched at the PSM/notochord (no) boundary (arrow) and at the cell periphery in the PSM and somitic mesoderm during somite formation (asterisks). (B) Longitudinal view of a stage 22 embryo showing accumulation of Xena at intersomitic boundaries. (C-E) In anterior regions (stage 18 embryo is shown), Xena and FN accumulate at presumptive somite boundaries prior to rotation. Arrow indicates accumulation at a newly formed boundary and arrowheads indicate accumulation at the next forming boundary. (F) In posterior regions (stage 22 embryo is shown), Xena accumulation at somite boundaries coincides with rotation. Arrow indicates accumulation at forming boundary; arrowhead shows lack of Xena enrichment in the PSM where the next boundary will form. (G) Cross-section of a stage 22 embryo showing Xena localization to cell-cell contacts within somites. (H) Xena is enriched at intermyotomal boundaries in stage 45 embryos. Anterior is towards the left in all images except G. Xena localization was visualized with antibodies raised against Mena (A,B) or Xena (C,E-H). Scale bars: 100 µm.