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Number and distribution of stapedius motoneurons in cats
Author(s) -
Joseph Michael P.,
Guinan John J.,
Fullerton Barbara C.,
Norris Barbara E.,
Kiang Nelson Y. S.
Publication year - 1985
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.902320105
Subject(s) - anatomy , biology , facial nerve , cochlea , brainstem , cats , reticular formation , acoustic reflex , neuroscience , reflex , nucleus , medicine
Abstract Cell bodies of stapedius motoneurons were identified by retrograde transport of horseradish peroxidase (HRP) following injections into the stapedius muscle. Large injections were made in an attempt to label all stapedius motoneurons. To control for labeling of non‐stapedial neurons resulting from spread of HRP, we determined the locations of brainstem neurons labeled by HRP applied to the facial nerve, the chorda tympani nerve, the auricular branch of the vagus nerve, the tensor tympani muscle, and the cochlea. In three cats analyzed in detail, 1,133–1,178 neurons projecting to the stapedius muscle were identified. Arguments are given which suggest that in these three cats all stapedius motoneurons were labeled. The labeled stapedius neurons may all be motoneurons because they all stain positively for acetylcholinesterase and have medium–coarse Nissl bodies. Most stapedius motoneurons were located around the motor nucleus of the facial nerve. Stapedius motoneurons were also found near the descending limb of the facial‐nerve root, in the peri‐olivary neuropil, and in the reticular formation with the ascending fibers of the facial‐nerve root.