Electron microscopy of the adrenergic and cholinergic nerve terminals in the mouse salivary glands.

5-Hydroxydopamine was used as a marker of adrenergic nerve elements. In the submandibular gland the most numerous innervation by both adrenergic and cholinergic terminals was in the peri-acinar connective tissue, although no nerve fibres occurred within the acini of this gland. Only the cholinergic type of nerves was occasionally found in close contact with parenchymal cells of the intercalated ducts, granular convoluted tubules and striated ducts. The parotid gland received adrenergic and cholinergic terminals in the acini, intercalated ducts and peri-acinar connective tissue, and the number of these terminals was less than in the submandibular gland. Comparison of the relative numbers of adrenergic and cholinergic nerve terminals showed that about 70 per cent of terminals seen in both glands were adrenergic in nature; the remaining 30 per cent were cholinergic. The sublingual gland received less frequent innervation than in the parotid or submandibular gland. In the sublingual and Ebner glands, the majority of peri-acinar terminals was cholinergic and adrenergic terminals comprised only 10–20 per cent and only the cholinergic type was found within the acini. The reaction products due to acetylcholinesterase activity appeared around both the adrenergic and cholinergic terminals in all four of glands.