Morphological changes in the salivary glands upon stimulation by receptor-selective agonists. III. Sublingual glands...

The innervation of the sublingual glands of the mouse by the atuonomic nervous system and the influence of receptor-selective mimetics of the neurotransmitter substances on these glands have been studied with histological techniques and have been compared with results of in vitro secretory experiments. The mimetics were administered either via an intraperitoneal injection or via the perfused blood vessels. The sublingual glands were predominantly innervated by the cholinergic nervous system. However, also some adrenergic nerves were observed in these glands, using the catecholamine fluorescence technique. The acinar mucous cells and serous demilune cells were stimulated to secrete their granules by pilocarpine, as expected on account of the innervation and the previously reported results of in vitro experiments. Isoprenaline and phenylephrine appeared to stimulate the release of granules from the demilune cells, despite the fact that only very few adrenergic nerves were found in these glands. These data suggested that the proteins secreted after stimulation with phenylephrine originated from the demilune cells. The way in which the acinar demilune - and mucous cells secrete their granules is not yet entirely clear. The demilune cells seemed to secrete in an exocytotic manner, apparently after an expansion of their luminal plasma membrane. The mucous cells did not secrete in an exocytotic way, but released the content of their granules after disruption of the apical plasma membranes.