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A fibril of a neuron, usually extending from the processes and traversing the cell body.



a microscopic filament that is found upon treatment of nerve cells—neurons—and the longest outgrowths of the nerve cells—axons—with silver salts and other reagents.

In the late 19th and early 20th centuries, neurofibrils were ascribed the function of conducting nerve impulses. This view proved to be erroneous when it was found that nerve impulses are conducted by the external membrane of the neuron. Electron microscopy revealed two kinds of longitudinal neurofibrils in the outgrowths of neurons: neurotubules and neurofilaments. Neurotubules are from 20 to 25 nm in diameter and are formed from the protein tubulin; they are believed to transport substances along the axon. The threadlike neurofilaments are formed from a protein similar to the muscle protein actin. Neurofilaments are especially numerous in the movable terminal portions of growing axons.

References in periodicals archive ?
Acetylcholine esterase staining activity is increased in the coarse parasympathetic neurofibrils present in the lamina propria and in the mucosae" according to MeierRuge, who did extensive research in congenital neuronal malformations.
After her death, 4 years after diagnosis, autopsy of Auguste's brain showed atrophy, tangled bundles of neurofibrils, and accumulations of an unknown substance in a miliary pattern.
Among the most notable are the appearance of plaques and tangles of neurofibrils within brain nerves that affect nerve synapses and nerve-nerve cell communication.