Table 1.

Summary of the myogenic phenotypes observed in the different compound mouse mutants analysed in this study

Mouse mutantsEpaxialHypaxial
Gli2-/- Gli3+/- Somite morphology normalNormal
Myf5 activation in DML cells reduced
Epaxial myotome expands ventrally
Gli2+/- Gli3-/- Somite morphology normalVentromedial expansion of hypaxial myotome (dermomyotomal markers Pax3 and Sim1 not affected)
Myf5 activation in DML cells is delayed
Epaxial myotome is delayed and reduced
Gli2-/- Gli3-/- Somite morphology altered (ventral epithelial extension of dermomyotome)Ventromedial expansion of hypaxial myotome (dermomyotomal markers Pax3 and Sim1 not affected)
Myf5 activation in DML cells is delayed
Epaxial myotome is delayed, reduced and expands ventrallyUpregulation of hypaxial migratory cells (Lbx1-positive)
Premature activation of Myod1
Shh-/- Somite morphology is altered (loss of medial dermomyotome)Ventromedial expansion of interlimb hypaxial myotome and dermomyotomal markers Pax3 and Sim1
No Myf5 activation in DML cells
No epaxial myotome
Shh-/- Gli3-/- Somite morphology restoredVentromedial expansion of interlimb hypaxial myotome
Normal Myf5 activation in DML cells and in epaxial myotomeDermomyotomal markers not tested
Ventral expansion of interlimb epaxial myotome
Shh-/- Gli2-/- Somite morphology is altered (loss of medial dermomyotome)Reduced expansion of interlimb hypaxial myotome (shift from ventromedial to dorsomedial)
No Myf5 activation in DML cells
No epaxial myotomeDermomyotomal markers not tested.