Membrane-bound glycoprotein in the alveolar cells of the caprine lung

An ultramicroscopic analysis of caprine lung glycoproteins, designed to detect plasmalemma-associated sulfoglycoprotein of alveolar type I and alveolar type II cells, was performed. High-iron diamine staining demonstrated a layer containing sulfated glycoproteins at the atypical plasmamembrane of alveolar type I cells and microvilli of alveolar type II cells. The cytoplasmic vesicles of the alveolar type I cell contained the reaction product on the inner leaflet of the vesicular unit membrane. The vesicles showed a variety of interactions with the apical plasma membrane. High-iron diamine staining also demonstrated sulfoglycoproteins in the cytoplasmic granules of the mast cells in the alveolar septum. The present study gives evidence that plasmalemma of the alveolar cells of the goat lung possesses exposed hyaluronic acid groups.