An Electron Microscopic Observation of the Nucleus of the Optic Tract in the Rat

Abstract

To determine the role of gamma aminobutyric acid (GABA) in the projection from the retinal ganglion cells to the nucleus of the optic tract (NOT), NOT of a rat in which the eyeball had been removed was observed by electron microscopy. In the observation of the nerve synapse bonding region in the NOT on the opposite site to the enucleated eyeball, Colonnior's symmetrical type was recognized, but the asymmetrical type was also recognized; they occurred at a ratio of 4: 3. The spherical type was more frequent than the flattened type in the NOT. In the electron microscopic observation of the NOT on the contralateral side, far more advanced vacuolation was confirmed in the neurons when compared with those of the collateral side. The optic nerves in rats do not intersect completely because the vacuolation showing a retrograde degeneration was observed also on the collateral side.
From these results, the inhibitory axon terminals in the NOT cannot be conclu d ed to have GABA activity.