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Evidence for prenatal competition among Ahe central arbors of trigeminal primary afferent neurons: Single axon analysis
Author(s) -
Chiaia Nicolas L.,
Zhang Shujie,
King Tod D.,
Rhoades Robert W.
Publication year - 1994
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.903450211
Subject(s) - biology , axon , brainstem , neuroscience , postsynaptic potential , trigeminal ganglion , axoplasmic transport , anatomy , horseradish peroxidase , afferent , somatosensory system , axon terminal , free nerve ending , sensory system , biochemistry , receptor , enzyme
Abstract Previous studies from this laboratory have demonstrated that prenatal damage to vibrissae follicles results in significant increases in the brainstem representations of the remaining vibrissae as demonstrated by staining for the mitochondrial enzyme cytochrome oxidase (CO). Because CO is primarily a postsynaptic marker, these results do not directly address the question of whether there were changes in the projections of primary afferent fibers. To address this issue, we made intra‐axonal recordings from individual vibrissa‐related primary afferents in rats that sustained damage to vibrissae follicles oil embryonic day 17, and then injected horseradish peroxidase (HRP) into these axons to visualize their terminal arbors in the brainstem at the level of trigeminal subnucleus interpolaris (SpI). All vibrissae‐related primary afferents responded to deflection of one and only one vibrissa, and the terminal arbors of axons (N = 47) recovered from animals that sustained fetal peripheral lesions were significantly larger than those (N = 23) from normal rats. Fibers from fetally damaged animals had increased total fiber lengths and numbers of branch points. These results indicate that reduced competition among primary afferent axons results in increases in the terminal arbors that remain. These increases occur without any significant alteration in their peripheral receptive fields. © 1994 Wiley‐Liss, Inc.