Hes7 is required for regular sacral segmentation in Lfng^−/− embryos, but need not oscillate.

(A, B) Segmentation in Hes7^−/− mice is irregular all along the axis (including the sacrum) as visualised by Uncx4.1 staining of embryos (A) and foetal skeleton preparation (B; top, lateral view; bottom, ventral view; scale bars are 5 mm). For annotation, see legend to Figures 3 and 2. (C) In situ hybridisation with a Hes7 intron probe to visualise active transcription (left) shows a clearly dynamic pattern in Lfng^+/− PSMs (top) but a strong background throughout Lfng^−/− PSMs (bottom). A Hes7 cDNA probe (C right) visualises dynamic transcript distribution in Lfng^+/− PSMs (top) but mainly ubiquitous staining in Lfng^−/− PSMs (bottom; embryos showing dynamic expression domain most clearly were selected).