STRUCTURE OF ENTEROCYTE TRANSCYTOSIS COMPARTMENTS DURING LIPID ABSORPTION

Transcytosis of lipids in adult rat enterocytes was studied. The Golgi was in a non transportable state and contained many bubbles, but did not have the inter cistern connections typical of cis bridge and trans bridge cisterns. After the addition of lipids in the form of chyme, the pre chylomicrons were initially found in the tubules of the smooth endoplasmic reticulum attached to the basolateral plasmalemma below the girdle, consisting of adhesive compounds always connected to other cisterns. The overload of enterocytes with lipids led to the accumulation of lipid droplets, an increase in the diameter of chylomicrons, and the transition of the Golgi complex to a transport state with the formation of intercisternal bonds, the attachment of cis and trans cisterns, and the disappearance of vesicles. This data is discussed from a functional point of view. Despite enormous progress in deciphering the molecular mechanisms involved in intracellular transport in cell culture and in vitro, many aspects of this in situ process remain unclear.