| Abstract: | The ultrastructural and cytochemical properties of the maxillary gland were investigated in 24 adult Sprague-Dawley rats of both sexes. The relationship between the interstitial cell and/or excitatory cholinergic terminals with the secretory cell was discussed. The secretory material containing primarily neutral lipids, proteins, carbohydrates and mucosubstances appeared electron-opaque following staining with uranyl acetate and lead citrate. Ruthenium red precipitated strongly on zymogenic granules which showed an increasing affinity for phosphotungstic acid, paralleling a rise in pH towards 7.7. The process of fusion of the plasma membrane with the membrane of secretory granules was observed, although some membrane-bound granules were identified in the acinar and ductal lumina. Intracellular membranous structures were best revealed with phosphotungstic acid at pH 1.0–1.5, whereas ruthenium red reacted primarily with lipid inclusions and tonofilaments. Acid phosphatase activity was predominantly limited to secondary lysosomes and, to a lesser degree, to primary lysosomes and Golgi saccules. The morphological and chemical properties of secondary lysosomes in the secretory cell suggested a pronounced hydrolytic activity related to lipid inclusions and endocytotic vesicles. |
