The effect of sympathectomy on the occurrence of microliths in salivary glands of cat as studied by light and electron microscopy.
Parasympathectomy is followed by a greatly increased occurrence of microliths in the feline submandibular gland, which appears to be because of secretory inactivity. The sympathetic nerves are also important in secretory processes, and so feline submandibular, sublingual and parotid glands subjected to postganglionic sympathectomy for periods from 1 day to 1 yr have now been investigated. Microliths were detected in two out of 28 sympathectomized submandibular glands and four out of 27 untreated glands, and in 10 out of 22 sympathectomized sublingual glands and seven out of 19 untreated glands. There were no significant differences between the occurrence of microliths in sympathectomized and untreated glands. Microliths were not detected in any of 29 sympathectomized and 30 untreated parotid glands. The appearance of the sympathectomized glands was similar to that of the untreated glands. The failure of sympathectomy to affect the occurrence of microliths or the appearance of the glands is possibly because of parasympathetic nerve impulses, which produce continuing secretory activity, and also the spontaneous secretion of the sublingual gland. The results support the concept that secretory inactivity is an aetiological factor of microlithiasis.