Rat Sublingual Salivary Glands: Secretory Changes on Parasympathetic or Sympathetic Nerve Stimulation and a Reappraisal of the Adrenergic Innervation of Striated Ducts

Sublingual glands were examined by light and electron microscopy after stimulating the parasympathetic nerve (5 Hz continuously) or the sympathetic nerve (50 Hz in bursts 1 s every 10 s) and compared with contralateral, unstimulated, normal glands from each animal. Parasympathetic stimulation caused secretion of mucin from the tubulo-acini and possibly a small amount of degranulation from the demilunes but no changes were detected in the striated ducts. Sympathetic stimulation, on the other hand, had no effect on the tubulo-acini or demilunes but caused a surprisingly extensive degranulation of the striated ducts plus loss of glycogen from their cells. Reassessment of the adrenergic innervation in the glands was therefore undertaken, by means of catecholamine fluorescence. This identified a regular association between adrenergic nerves and the striated ducts not only in sublingual but also in submandibular glands; features that have not previously been recognized. There was, however, only a sparse adrenergic innervation of the other parenchymal elements in the sublingual glands.