WGA-HRP studies on the fiber connections from the spinal cord to the Deiters' nucleus

The labyrinthine-spinal reflexes are influenced by the inputs from the cervical and lumbal propriocepters. We studied the afferent route by the retrograde WGA-HRP method in cats. After the injection of WGA-HRP into either the dorsal or the ventral Deiters' nucleus, labeled neurons were investigated in the spinal cord, the cerebellum, the contralateral vestibular nucleus complex and the brain stem nucleus. In this paper, we report the results in the spinal cord of cats. i) When WGA-HRP was injected into the dorsal Deiters' nucleus, labeled neurons in the spinal cord were found mainly extending from the cervical to the lumbosacral area of the spinal cord. A number of labeled cells were located predominantly in the contralateral cervical segments, while a small number of labeled cells was found ipsilaterally in the lumbosacral segments. ii) In the case of the ventral Deiters' nucleus, labeled neurons were found extending from the cervical to the upper thoracic area of the spinal cord. Localization of labeled neurons in the spinal cord was limited mainly to Rexed's laminae VII and VIII. These results suggest that the afferent fibers from the spinal cord to the Deiters' nucleus are closely related to the labyrinthine-spinal reflex.