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NADPH‐diaphorase histochemistry reveals an autonomic‐like innervation in the postnatal hamster cochlea
Author(s) -
Morris JohnClay K.,
Phelps Patricia E.,
Simmons Dwayne D.
Publication year - 1999
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/(sici)1096-9861(19990927)412:3<458::aid-cne6>3.0.co;2-f
Subject(s) - biology , cochlea , hamster , immunohistochemistry , neuroscience , anatomy , endocrinology , immunology
Previous studies used nicotinamide adenine diphosphate (NADPH)‐diaphorase histochemistry as an indicator of nitric oxide synthase (NOS) expression in the adult mammalian cochlea. In this study, we investigated the early postnatal expression of diaphorase activity in the hamster cochlea. Two types of extrinsic fibers were intensely labeled as early as postnatal day 3 (P3) in the portion of the cochlear nerve that innervates the base of the modiolus. By P10, these fibers had reached the spiral ganglion and were projecting toward the organ of Corti. The perivascular type of fiber did not project into the organ of Corti; however, the nonperivascular type could be traced among the supporting cells below the outer hair cells. Spiral ganglion cell somata were also labeled as early as P3. The onset of diaphorase expression in the spiral ganglion cells corresponds to a critical period of synaptogenesis for these sensorineural cells. If NADPH‐diaphorase activity is an indicator of NOS, then our results suggest that NO may play a role during postnatal cochlear development. J. Comp. Neurol. 412:458–468, 1999. © 1999 Wiley‐Liss, Inc.