The orientation of the wing mesenchyme influences the direction of the migration of myoblasts in the avian embryonic wing bud.

In order to analyze the influence of the orientation of the wing bud mesenchyme on the proximodistal direction of the migration of myoblasts in the avian embryonic wing bud, blocks of wing-bud mesenchyme were cut out and rotated around a dorso-palmar axis through 90 degrees or 180 degrees. Tissues originating from the quail wing bud and containing myoblasts were grafted into the space between the wing mesenchyme and the rotated blocks of mesenchyme proximal to the latter. In all experiments the donor-embryos were older than the acceptor-embryos. From HH stage 24 on, the rotation of the block of mesenchyme inhibited the migration of the myoblasts in a distal direction. We therefore propose that the orientation of the wing bud mesenchyme has an influence on the migratory behavior of myoblasts. This influence could provide "directional information" for the migrating myoblasts, allowing the migration of myoblasts in a distal direction only.