There is evidence that oligodendrocytes in the spinal cord are derived
from a restricted part of the ventricular zone near the floor plate.
An alternative view is that oligodendrocytes are generated from all pa
rts of the ventricular zone. We reinvestigated glial origins by constr
ucting chick-quail chimeras in which dorsal or ventral segments of the
embryonic chick neural tube were replaced with equivalent segments of
quail neural tube. Ventral grafts gave rise to both oligodendrocytes
and astrocytes. In contrast, dorsal grafts produced astrocytes but not
oligodendrocytes, In mixed cultures of ventral and dorsal cells, only
ventral cells generated oligodendrocytes, whereas both ventral and do
rsal cells generated astrocytes. Therefore, oligodendrocytes are deriv
ed specifically from ventral neuroepithelium, and astrocytes from both
dorsal and ventral.