MONOAMINE OXIDASE DISTRIBUTION IN THE RABBIT EYE

Monoamine oxidase distribution in the different components of the eye has been described in detail. The degree of enzyme activity varied from one component of the eye to another, the corneal stroma and Descemet's membrane being completely negative. The corneal epithelium, choroid and nonpigmented cells of the iris stroma showed mild positive activity. Strong positive activity was present in the myelin sheaths of optic and oculomotor nerves and also in the ciliary epithelium. The irido-corneal angle (meshwork) showed a moderately strong positive activity against the surrounding tissues. The most interesting observations were made in the retina. The pigment epithelial cell layer and the outer plexiform layer showed moderate positive activity while the activity in the inner plexiform layer, the outer and inner nuclear layers and in the ganglion cell layer was negligible. The layer of nerve fibers and internal limiting membranes were completely negative. In the layer of neuroreceptors, the outer half of this layer gave a very strong positive reaction and the inner half a very mild positive reaction. The significance of this varied distribution in the neuroreceptor layer is discussed. A comparison of distribution of some important enzymes in the myelin sheaths of peripheral nerves, pigment epithelial cells of the retina, and the inner and outer segments of the neuroreceptor layer is made to show that each tissue is differently equipped with various enzymes, due probably to a fundamental difference in their functions.