Electron Microscopic Examination of the Cat Oculomotor Nucleus Innervating the Medial Rectus Muscle.

Lee, Saeng Ho; Yoo, Joong Ha

Original Article

Journal of the Korean Ophthalmological Society 1998;39(6):1231-1236.
Published online June 1, 1998.

Electron Microscopic Examination of the Cat Oculomotor Nucleus Innervating the Medial Rectus Muscle.

Saeng Ho Lee, Joong Ha Yoo

Department of Ophthalmology, College of Medicine, Inha University, Sungnain, Korea.

고양이의 내직근지배 동안신경핵의 전자현미경적 연구

이생호(Saeng Ho Lee),유중하(Joong Ha Yoo)

Abstract

Oculoinotor nerve is a very important nerve in the ophthalornology, innervating the medial rectus, inferior rectus, inferior oblique, superior rectus, levator palpebrae superioris, and the presynaptic parasyrnpathetic outflow to the internal muscles of eye (the ciliary muscle and the sphincter muscle of the iris) . To examine the fine structure of neurons and synapses in the oculomotor nucleus projecting the rnedial rectus Hiuscle, 50% horseradish peroxidase (HRP) solution was injected into the rnedial rectus rnuscle of the cat, and serial sections of midbrain were studied with electron microscopes. Large motor neuron, small motor neuron and spindleshape motor neuron were examined. Cell body contained rich organells that. were nucleus, rough endoplasmic reticulum, HRP containing lysosorne, mitochondria and ribosome etc. Three kinds of synapses that are axosomatic synapse, axo-dendritic synapse and axo-axonic synapse were examed. Moreover, the nerve terminals had spherical-shaped synaptic vesicles. These results suggest that the function of inotorneurons related to the medial rectus muscle is not. defined by the shape and distribution of nerve terrninals but. depends on the shape of synaptic vesicles.

Key Words: Cat;Electron rnicroscope;Horseradish peroxidase (HRP);Oculomotor nucleus