Expression of high-molecular-weight neurofilament protein and vimentin in human developing spinal cord and dorsal root ganglia

Expression of intermediate filament proteins in developing human dorsal root ganglia and spinal cord was studied using double-label immunofluorescence on frozen sections with monoclonal antibodies to vimentin and high-molecular-weight neurofilament protein (NF-H). Both proteins were found in the nerve fibres inside the ganglia of 6- and 8-week embryos. In 9-14-week embryos the NF-H protein was found in the perikarya of ganglion cells. Vimentin was only sporadically present in these cells, but was accumulated in connective tissue cells. In the following development the NF-H protein expression was limited to the ganglion cells and processes, and vimentin was confined to the satellite cells and mesenchymal derivatives. In the spinal cord of the 6-week and 8-week human embryos NF-H protein was found in the longitudinal fibres of the marginal layer and in a loose network of nerve fibres in the mantle zone. Some of the nerve fibres were also vimentin positive. The coexpression of both proteins stopped during weeks 9-10. In 30-week foetuses vimentin was only found in glial cells and mesenchymal derivatives, while NF-H protein was in the axons of both white and grey matter but not in neuronal perikarya.