Cellular heterogeneity in the ependymal layer of the chicken's lumbosacral spinal cord

Cytological development in the ventricular zone of the chicken's lumbosacral spinal cord was studied by light and transmission electron microscopy before and after hatching. Two morphologically distinct types of cell were first noted by embryonic stage 41 and were present in the 2-day-old chick. From cell bodies located at the border of the ependymal layer, a lightly stained process extended among the more numerous and typical ependymal cells to reach the central canal. Synapses were observed only on the cell bodies of the lightly stained cells.