Morphological changes in lipid droplets within cells of the duodenal transition zone in suckling rats.

This ultrastructural study compares the lipid droplets within epithelial cells at the bases of the duodenal villi in the transition zone between crypts and the lateral portions of the adjacent villi in newborn rats suckled 24 h, 10 days and 15 days and contrasts with cells in similar locations in newborn unsuckled and weaned rats. The mean diameters and numbers of lipid droplets per field decreased when cells from rats at 10 and 15 days of age were compared to those at 24 h of age. The range of sizes also narrowed. There was cell-to-cell variability in number and in opacity of the lipid droplets. Multiple membranous laminae enclosed the droplets. Cells in similar locations in newborn unsuckled and in weaned rats did not contain lipid droplets. It is concluded that the numbers and sizes of the large lipid droplets within cells in the transition zones at the bases of the villi decrease as cells at the same relative locations mature during suckling and as the infant rats mature.