Tendon Progenitor Cells (LB)

Tendon progenitor cells of the limb originate in the lateral plate mesoderm and are defined as Scleraxis-positive cells. In contrast to axial tendon formation, limb tendon progenitor cells are not localized within a specific compartment in the limb bud mesenchyme. Instead, they are intermingled with the migrating myoblasts in the dorsal and ventral parts of the limb bud. Scx-positive cells are first detected in the limb bud on E9.5 of the mouse embryonic development. The initial induction of Scx-positive cells is not dependent on signaling from muscle progenitor cells, but rather on signaling from the overlying limb surface ectoderm. The nature of this ectodermal signaling is still elusive.