Early appearance in neural crest and crest-derived cells of an antigenic determinant present in avian neurons

A monoclonal antibody (" E C8") against chicken dorsal root ganglion cells has been produced. The epitope (antigenic determinant) to which this antibody binds appears in neuronal cells-of both the peripheral and central nervous systems-and in a limited number of nonneuronal cell types in avian embryos. The epitope is intracellular and is probably part of a protein as judged by its susceptibility to proteases. This epitope appears very early in neuronal development. It may be detected in brain, spinal cord, and ventral root nerve fibers of Hamburger-Hamilton stage 16 chicken embryos (51-56 hr of incubation). At this same age, E C8-immunoreactive cells can be found in the neural crest migratory space between the neural tube and the somite about a day before dorsal root ganglia begin to coalesce. Since some cultured neural crest cells (but not somitic mesenchymal cells) also express this epitope, we propose that the E C8 monoclonal antibody identifies an early differentiating subpopulation of neural crest cells which express this putative neuronal trait soon after the time of cessation of migration in vivo.