Distribution of Sar1 proteins in duodenal biopsies from healthy individuals and AD patients. Immunostaining for Sar1 proteins in normal control subjects (a) was detected mainly in the villus tip (black arrows) in the apical part of the enterocytes. The villi exhibit a heterogeneous aspect: immunolabelling occurs predominantly on one side (black arrows) and is largely absent on the other side (empty arrows). In patients with AD, AD2 (b) and AD3 (c), the immunolabelling for Sar1 was present in the same area of the villi but was clearly decreased in intensity as compared to normal individuals. The immunostaining was detected around the large lipid droplets which distended the cytoplasm of the enterocytes. The same heterogeneous aspect observed in the normal individuals was also seen in the AD subject with staining appearing as slightly positive on one side (black arrows) and negative on the other side (empty arrows). No staining was seen when the primary antibody was omitted (d). (Fig. a ×20; b, c, d, × 10; insert × 40).