Retrograde transport of NGF by early chick embryo spinal cord motoneurons.

Neuronal retrograde transport of nerve growth factor (NGF) was examined in chick embryos at 5, 6, and 7 days of incubation. Radiolabeled NGF was injected in the target limb muscle and the retrograde transport was viewed following processing for autoradiography. Silver grains were localized in the peripheral nerve, in the ventral root, in neuronal cell bodies within the dorsal root ganglion, and in motoneurons of the lateral motor column. Comparable injections of 125I-cytochrome c resulted in the presence of label at the peripheral injection site only. The possible developmental significance of these observations is discussed.