Structural studies of human saliva.
Samples of mixed saliva and of parotid and sublingual/submandibular saliva fractions from four donors were subjected to instantaneous solidification in liquid nitrogen followed by sectioning in a microtome/cryostat. The sections were stained with hematoxylin-eosin, periodic acid-Schiff, Alcian blue, Oil-red-O, or Sudan Black B and then examined at the light-microscopic level. In all the sectioned samples several previously never described features were observed, the most pronounced of which were a loose overall network structure and collections of lipoid droplets often in a loose arrangement. In the mixed saliva sample sections many of the microorganism-like structures were observed in large bunches associated with epithelial cells and densely staining saliva components. The present method was tested in a series of experiments for possible errors.