Electron microscopic and cytochemical study on the role of golgi elements and plasma membrane of enterocytes in the intestinal lipid transport.

Abstract

Intestinal lipid absorption and transport were investigated in albino rats. The observations point towards the existence of a continuity between plasma membrane invaginations and elements of the Golgi complex on its “mature” face. They also suggest a segregation of lipid droplets by paired Golgi membranes and plasma membrane invaginations. The following way for lipid transport is deduced: lipid droplets moving inside the smooth endoplasmic reticulum accumulate progressively and are condensed in Golgi cisternae of the “forming” face. Their limiting membrane ruptures and liberated lipid droplets are segregated by paired Golgi membranes of the “mature” face or by plasma membrane invaginations. Subsequently the inner of the two “segregating” membranes disappears while the lipid droplet is moved towards the intercellular space inside a canal communicating with this space. The suggestion is made that the Golgi apparatus is of double origin: one component representing a terminal plication of the endoplasmic reticulum; the second one—a terminal plication of the plasma membrane invagination. This concept explains the ultrastructural and histochemical differences between Golgi membranes of the “forming” and “mature” faces of the complex.