Ultrastructure of cat superior vestibular commissural neurons.
The ultrastructure of the feline superior vestibular commissural neurons (CNs) was studied after labeling by contralateral injection of horseradish peroxidase. These small spindle-shaped cells are found in clusters oriented in a rostrocaudal, dorsoventral or lateromedial direction. The CNs have a cleft nucleus, with the majority of nerve terminals contacting the CN near the emergence of polar dendrites. Polarization of the afferent synaptic profiles suggests a bidirectional nature of inputs to CNs by the vestibular nerve, contralateral CNs, and/or cerebellar systems. One type of labeled cell does not conform to this pattern, instead resembling a vestibulo-ocular neuron. Hence, it may function as a commissural and a vestibulo-ocular neuron. Characterization of different types of synapses, based on the size and eccentricity of their synaptic vesicles, indicates a continuum rather than separate populations. Volume fraction of intracellular organelles showed a larger volume fraction percent of polyribosomes in larger cells. Since this organelle is involved with protein synthesis, this finding may indicate that larger CNs have a more extensive dendritic tree.
Guyot
J P
JP
Department of Otolaryngology and Communication Sciences, State University of New York Health Science Center, Syracuse 13210.
Lyon
M J
MJ
Gacek
R R
RR
D000222:Adaptation, Physiological; D000818:Animals; D002415:Cats; D002467:Cell Nucleus / Q000648:ultrastructure; D003712:Dendrites / Q000648:ultrastructure; D006735:Horseradish Peroxidase; D008854:Microscopy, Electron; D009434:Neural Pathways / Q000648:ultrastructure*; D009474:Neurons / Q000648:ultrastructure*; D015388:Organelles / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure; D014726:Vestibular Nuclei / Q000648:ultrastructure*
D006735:Horseradish Peroxidase