Figure 1.

Pax3⁺ somitic cells give rise to all Pax7⁺ cells and embryonic myoblasts, while Pax7⁺ cells give rise to only a few myoblasts at E12.5 in the limb. (A–H) All Pax7⁺ cells and MyoD⁺ embryonic myoblasts are β-gal⁺ in E12.5 Pax3^Cre/+;R26R^LacZ/+ hindlimbs. (I–L) Only a few proximal MyoD⁺ myoblasts are β-gal⁺ in E12.5 Pax7^iCre/+;R26R^LacZ/+ hindlimbs.