Fig. 7. Genetic analyses using double-knockouts of Ripply2 and either Lfng or Mesp2. The skeletal morphologies and Uncx4.1 expression patterns were compared among wild-type (A), Lfng-null (B), Ripply2/Lfng double-null (C), Mesp2-null (D) and Ripply2/Mesp2 double-null (E) E17.5 fetuses or E9.5 embryos. The skeletal defects in the Ripply2^-/- fetus were found to be further enhanced by the additional loss of Lfng, and the pedicles of the neural arches were almost completely absent in this compound-null fetus (C). By contrast, the Ripply2/Mesp2 double-null fetus (E) shows a similar morphology to that of the Mesp2 single-null fetus (D). The Uncx4.1 expression pattern was independently examined at E10.5 (A, n=2; B, n=2; C, n=1) and E9.5 (A, n=4; B, n=2; C, n=2; D, n=4; E, n=2). Only representative images of E9.5 embryos are shown.