Human nuclear antigen-positive cells (a) double stained with Isl-1 (b; red), p75 (c; p75 in red, human nuclei in green), or ChAT (d; ChAT in blue, human nuclei in brown), consistent with a MN lineage of mixed maturation state. (e) Some human cells in the ventral horns were surrounded by synaptophysin positive processes, suggesting integration with host tissue (synaptophysin in red, human nuclei in green). (f) Many human cells extended Tuj1 positive processes, and in some animals, ectopic motor tracts were present in the dorsal and ventral white matter (Tuj1 in red, human nuclei in green). Bar = 100 µm for (a) and (b), 50 µm for (c) and (e), 10 µm for (d), 200 µm for (f).