Differences in sialic acid expression of lung alveolar cells between normal and intrauterine growth-retarded rat...

The expression of sialic acid on the luminal surface of lung alveolar epithelial cells was compared in normal developing and intrauterine growth-retarded (IUGR) rat fetuses during the late gestational and early neonatal periods using neuraminidase treatment of the tissues and staining with a galactose-binding lectin from peanut. In IUGR fetal lung tissues, there were more staining for free galactosyl residues (before neuraminidase treatment) and less staining for sialic acid-bound galactosyl residues (after neuraminidase treatment) than in normal fetal lung tissues during the developmental stages. The staining reaction after neuraminidase treatment was mostly confined to the type 2 alveolar cell surfaces especially on microvillous surfaces. These findings suggest that in IUGR rat fetuses galactosyl residues of the lung alveolar epithelial cell surfaces are not sufficiently masked with terminal sialic acids resulting in a disturbance in the normal maturation process of the alveolar epithelial cells.