The distribution of muscle fibre types in chick embryo wings transplanted to the pelvic region is normal.

Chick embryo wing buds were transplanted to the pelvic region in place of, or in addition to, the hindlimb bud prior to innervation. The wrist muscle ulnimetacarpalis dorsalis (umd) was innervated by middle-dorsal or middle-ventral motoneurons in the lumbar lateral motor column (LMC) in a rostrocaudal position which varied with the rostrocaudal position of the wing. Despite the heterotopic innervation the subsequent development of the distributions of fast and slow muscle fibres, as judged by ATPase staining, was normal in all muscles examined. The pattern of innervation in the umd, as judged by acetylcholinesterase staining also developed normally. It is probable that muscle fibre type is intrinsically, not neurogenically, determined.