Ultrastructure of Weber's salivary glands of the root of the tongue in the rat.

BACKGROUND: The mammalian tongue encompasses several sizeable agglomerations of minor salivary glands. The ultrastructure of the various glands in the body of that organ has already been determined. In contrast, almost nothing is known of the structure of Weber's glands, a collection of salivary glands in the root of the tongue. METHODS: The entire tongue was extirpated from anesthetized adult male rats that had been perfused with fixative and specimens of tissue that included Weber's glands were dissected from the lingual root. These were prepared for electron microscopic examination by conventional means. RESULTS: Weber's glands in the rat are mixed glands, consisting of long mucous tubules that often are capped by serous demilunes. There appear to be no ducts per se, the mucous tubules increasing in caliber and approaching the crypts of the dorsal lingual surface while still retaining their mucous secretory character. As these ducts near the surface, their lining changes to stratified squamous epithelium. The mucous cells are cytologically similar to those in the sublingual glands of the same animal. Mucous droplets undergo vertical fusion to form centrally situated intracellular channels through which mucus is exocytosed, much in the same manner as goblet cells. The serous cells, which have all of the hallmarks of protein-secreting cells, probably empty their secretory granules via cellular extensions that directly reach the tubule lumen since there are no intercellular canaliculi between adjacent mucous cells. CONCLUSIONS: The mucus elaborated by Weber's glands undoubtedly aids in swallowing dry food. We postulate that the serous cells in these glands, as in the more anterior von Ebner's glands, might play a role in the mechanism of taste, especially where posteriorly situated, nonlingual taste buds are concerned.