Role of Wnt-6 in limb myogenesis.

Cells from the ventrolateral lip of the dermomyotome at limb levels undergo epithelio-mesenchymal transition and migrate as individual and undifferentiated cells into the limb buds. The precursor cells are under the influence of various signaling factors in the limb. Dorsal and ventral ectoderm influences various aspects of limb development. In addition to our previous studies, we investigated the influence of ectoderm and Wnt-6 on somitic cells in the limb bud. We show that in the absence of ectoderm the precursor cells never form muscle cells but differentiate into endothelial cells. In addition, we show that Wnt-6 that is secreted from the ectoderm influences the precursor cells to form muscle even in the absence of ectoderm. This indicates that Wnt-6 is an ectodermal signal that induces somite-derived progenitor cells to form muscle cells during limb development.