[Identification of the vestibular projections in the oculomotor nuclei in the cat by autoradiography and electron microscopy].
The projection of vestibular pathways to the oculomotor nuclei ws investigated by electron microscopic radioautography. Unilateral injection of tritiated amino acids into the rostral vestibular complex was used in order to characterize the location and to identify the different types of labeled synaptic terminals involved in these pathways. In the normal oculomotor nuclei, 4 types of synaptic boutons were identified. Following the labeling of the vestibular synapses, in the ipsilateral oculomotor nucleus, types I and II boutons are the most prominent group and make up 75% of the synaptic vesicles, they are distributed on the cellular soma and the large dendrites of the oculomotor neurons. In contrast, in the contralateral oculomotor nucleus, type III boutons which are smaller and have larger diameter synaptic vesicles were predominant; they are prevalent on the distal part of the dendritic tree. From the results obtained, a relationship between the present anatomical findings and previously published physiological studies is established. The following conclusion is suggested: the inhibitory vestibular inputs probably terminate on the oculomotor neurons by these large types I and II boutons and the excitatory vestibular inputs by the smaller type III boutons. Also discussed is the complexity of the pattern of afferentation and the functional arrangement of the oculomotor nuclei.
D000818:Animals; D001345:Autoradiography; D002415:Cats; D003712:Dendrites / Q000648:ultrastructure; D004292:Dominance, Cerebral / Q000502:physiology; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000648:ultrastructure; D009434:Neural Pathways / Q000033:anatomy & histology; D009802:Oculomotor Nerve / Q000033:anatomy & histology*; D013569:Synapses / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure; D014725:Vestibular Nerve / Q000033:anatomy & histology*; D014726:Vestibular Nuclei / Q000033:anatomy & histology
Identification des terminaisons vestibulaires dans les noyaux oculomoteurs communs chez le chat par radioautographie en microscopie electronique.