Electron microscopy of duodenal biopsies of patients with AD. As shown for AD3 (a, b, c) and AD2 (d, e), two types of particles are apparent in the enterocytes in these patients (a,d): large lipid droplets, free in the cytoplasm (L), and smaller, lipoprotein-sized like particles (Lp), surrounded by a membrane. A higher magnification shows in (b) some individual lipoprotein-sized particles surrounded by a membrane (*) near a Golgi apparatus (G) which appears distended but devoid of particles and in (c,e) numerous lipoprotein-sized particles accumulated in a membrane bound compartment (membrane, white arrow). The intercellular spaces are empty. The cell nucleus is labelled N.