Abstract
The appearance of neurofilaments (NFs) and vimentin (Vim) in the nervous system of the mouse embryo was documented using immunohistochemical techniques. The three NF protein subunits appear early and simultaneously in central and peripheral neurons at 9 to 10 days of gestation. The onset of NF expression is concomitant with axon elongation and correlates extremely well with neurofibrillar differentiation and, in the case of autonomic ganglia, with the expression of adrenergic neurotransmitter properties. In the central and peripheral nervous system, NF expression is preceded by that of Vim, and both types of intermediate filaments coexist within the same cell for a short period of time.