Ultrastructural and histochemical observations on microcalculi in chronic submandibular sialadenitis

A search for microcalculi was made in 14 cases of chronic submandibular sialadenitis. Microcalculi were found in all cases. They were within serous acinar cells and ductal cells, within lumina, and interstitially. They were stained variably by periodic-acid/Schiff and Alcian Blue at pH 2.5. Ultrastructural analytical examination showed them to consist of crystals containing calcium and phosphorus. The observations support the possibility that microcalculi form in autophagosomes, enter lumina and occasionally become impacted to produce sialolithiasis and sialadenitis.