Comparative Distribution of Carbohydrates and Lipid Droplets in the Golgi Apparatus of Intestinal Absorptive Cells

Complex carbohydrates have been demonstrated cytochemically in the Golgi apparatus of the rat intestinal absorptive cell by specific stains for acid mucopolysaccharides (4) and for glycoproteins (15) . A staining gradient in the cisternae was observed in these studies, increasing towards one face of the Golgi apparatus, generally referred to as the mature face . In addition, the early accumulation of labeled carbohydrates from radioactive precursors has suggested an involvement of the Golgi apparatus in the synthesis of this product for transport to other positions (2, 6, 9, 14) . In the absorptive cell, much of this carbohydrate is subsequently transported to and incorporated into the surface coat, especially that covering the microvilli . Lipid droplets are common in absorptive cells of animals on a normal diet. In the Golgi apparatus, these droplets are present in varying numbers, depending on the absorptive state of the cell, and they show a preferential accumulation in vacuolar dilations of the cisternae closest to the plasma membrane (7, 11) . There is some evidence to suggest that these droplets represent chylomicrons or lipoproteins formed during lipid absorption and destined for release from the cell along the lateral boundaries (5, 7, 10) . A simultaneous occurrence of carbohydrates and lipid droplets in the Golgi apparatus and their respective distributions have not been demonstrated previously. A bifunctional condition is presently described in which the lipid droplets and carbohydrates are processed primarily on opposing faces of the Golgi apparatus .