The distribution pattern of the avian alpha 6 integrin subunit was examined during early stages of development. The results show that this subunit is prevalent in cells of the developing nervous system and muscle. alpha 6 is first observed on neuroepithelial cells of the cranial neural plate and trunk neural tube. With time, immunoreactivity becomes prominent near the lumen and ventrolateral portions of the neural tube, co-distributing with neurons and axons, particularly notable on commissural neurons. The alpha 6 expression pattern is dynamic in the neural tube, with immunoreactivity peaking by embryonic day 6 (stage 30) and decreasing thereafter. The ventral roots and retina exhibit high levels of immunoreactivity throughout development. In the peripheral nervous system, alpha 6 immunoreactivity first appears on a subpopulation of sympathoadrenal cells around the dorsal aorta and later in the dorsal root ganglia shortly after gangliogenesis. Immunoreactivity appears on prospective myotomal cells as the somites delaminate into the dermomyotome and sclerotome, remaining prominent on myoblasts and differentiated muscle at all stages. The mesonephros also has intense immunoreactivity. In the periphery, alpha 6 immunoreactive regions often in proximity to laminin, which is thought to be the ligand of alpha 6 beta 1 integrin.