Distribution of adrenergic nerves in the lacrimal glands of guinea-pig and rat.

The distribution of adrenergic nerves in the ex- and intraorbital lacrimal glands of guinea-pig and rat was studied using the sucrose-potassium phosphate-glyoxylic acid (SPG) technique. Blood vessels and secretory acini of guinea-pig lacrimal glands were demonstrated as having a rich adrenergic innervation. Adrenergic fibers in the rat were, however, much more sparse, and most of them were seen in association with glandular blood vessels, with only a few being found between secretory acini. Pretreatment of animal with a monoamine oxidase inhibitor and L-dopa did not change the morphological distribution of catecholamine fluorescent fibers, although the treatment improved the fluorescence, especially in the rat. Extirpation of the ipsilateral superior cervical ganglion eliminated all the fluorescent fibers in both normal and pretreated animals. The presence of adrenergic innervation of the lacrimal glands, especially in close connection with secretory acini, supports the theory that catecholamine-containing nerves play a role in the regulation of lacrimal secretion.