Sympathetic nerves to the rat cornea

The adrenergic innervation of the rat cornea was investigated by using the formaldehyde induced fluorescence (FIF) technique. The fluorescent nerves were observed mainly in the corneal stroma. Either cervical sympathectomy or pre-treatment with reserpine completely abolished the fluorescence of the adrenergic nerves of the cornea. After a stereotactic coagulation of the ophthalmic division of the trigeminal nerve, no adrenergic fibres were visible in the cornea and the number of the fluorescent iridic nerves was also reduced to a marked extent. On the other hand, ciliary ganglionectomy seemed to have no effect on the adrenergic fibres of the cornea. When the rats had been pre-treated with a monoamine oxidase inhibitors, nialamide, and noradrenaline, not only was there an increase in the intensity of the specific fluorescence, but also in the number of adrenergic nerves in the cornea. The epithelium was also shown to contain adrenergic nerves by administering high doses of nialamide combined with noradrenaline, both intravenously as well as topically on the cornea, under the protection of propranolol. It may be concluded that the rat cornea receives its adrenergic innervation along the posterior ciliary nerves. The short ciliary nerves do not appear to carry sympathetic nerves to the cornea.