Electron microscopic observations on cell coat and membrane-coating granules of the epithelium of the hard and soft palate in the rat

Abstract

Carbohydrate-containing compounds, probably glyco-proteins, were demonstrated in the epithelia of rat hard and soft palate by means of the periodic acid-thiocarbohydrazide-silver protein method. In hard palate there were two sites of positive staining. On the superficial surfaces of the cells of the stratum corneum and the stratum granulosum there was discontinuous coarse-globuled silver staining which did not pass through desmosomes. Its distribution was apparently correlated with the discharge of membrane-coating granules from the cells. On the orally exposed surfaces of stratum corneum, there was a variable, continuous, finely globular stained layer probably of salivary origin. Cytoplasmic staining was restricted to membrane-coating granules and was found just within their limiting membranes. It is proposed that, when the granules are released from the cell, their membranes are incorporated into the plasma membrane so that the glycoprotein component comes to lie on the surface of the cell where it persists until desquamation. In the soft palate epithelium, the only staining observed was that on the oral surface and probably of salivary origin. Secretion droplets in mucous glands of the soft palate were prominently stained.