Type II cochlear ganglion cells in the chinchilla

Mario A. Ruggero, Peter A. Santi, Nola C. Rich

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


In order to ascertain whether Type II cochlear ganglion cells project to the brain, we have studied the retrograde transport of horseradish peroxidase (HRP) from the cochlear nucleus to the spiral ganglion of the chinchilla. In this animal there exist two types of ganglion neurons, which closely correspond to those previously described in guinea pigs, cats and rats. As in the guinea pig, the majority population (Type I) consists of relatively large, myelinated neurons. The minority population (Type II, 10% of the total population) consists of small, mostly unmyelinated cells, with filamentous cytoplasm and finely grained nuclear chromatin. Type II neurons tend to be clustered toward the peripheral side of Rosenthal's canal, often in close proximity to the intraganglionic spiral bundle. By 24 h after injections of HRP into the cochlear nucleus, incubation of the cochlear ganglion in diaminobenzidine/H2O2 reveals abundant HRP label in both Type I and Type II neurons. Type II neurons, however, tend to be labelled less intensely than Type I neurons. Control experiments, consisting of spillage of HRP solution over the cochlear nucleus, were carried out to determine how much HRP might be picked up by neurons after HRP diffusion. Comparison of cochleae from injected animals and from the control animals suggests that most of the label that was found in ganglion neurons after cochlear nucleus injections represents axonally transported HRP. We conclude, at least tentatively, that Type II neurons project to the brain. The fact that less label is found in Type II neurons than in Type I neurons suggests that the former have thinner axons and/or finer terminals in the cochlear nucleus.

Original languageEnglish (US)
Pages (from-to)339-356
Number of pages18
JournalHearing Research
Issue number3
StatePublished - Dec 1982

Bibliographical note

Funding Information:
Bilk&h Lakhani was responsible for much of the serial sectioning. W.D. Ward and two anonymous reviewers provided constructive criticisms of an earlier version of this paper. Carolyn Reckman typed the manuscript. The authors were supported by NINCDS grants NS12125 and NS16799.


  • Type II neurons
  • VIII nerve
  • cochlear ganglion
  • horseradish peroxidase


Dive into the research topics of 'Type II cochlear ganglion cells in the chinchilla'. Together they form a unique fingerprint.

Cite this