MyoD − epiblast cells form skeletal muscle (red) if the BMP pathway is blocked.
The group has isolated a pool of cells from the embryonic epiblast that seems to be committed even before gastrulation to form skeletal muscle. These cells express mRNA for the MyoD transcription factor and form skeletal muscle in vitro if dissociated from other epiblast cells. Muscle formation in vitro requires a switch in expression from E- to N-cadherin, which also occurs as epiblast cells undergo gastrulation in vivo.
If separated from the muscle precursors, cells lacking MyoD retained E-cadherin and did not make muscle. However, when the MyoD− cells were treated with medium from the muscle precursors, they expressed N-cadherin and formed skeletal muscle. BMP-4 was able to block this inductive effect,...
