The autonomic innervation to the eye of monkey, cat and rabbit was studied using a sensitive histofluorometric method for adrenergic nerves and the acetylcholinesterase technique for cholinergic nerves.
In the monkey cornea adrenergic nerves are absent while they are numerous in both the cat and rabbit. There is marked species variation in the amount of autonomic innervation to the filtration area. The iris sphincter and the ciliary muscle have a dual innervation but the relative amount of the adrenergic component to these structures varies widely. The ciliary process in every case has a plentiful adrenergic nerve supply. In the choroid a heavy adrenergic innervation apparatus approaches the choriocapillaris. A layer of fluorescent terminals is found in the retina at the junction of the inner nuclear and inner plexiform layers in all three species. In the adjoining part of the inner nuclear layer lie scattered catecholamine-containing amacrine cells.