Localization of endoplasmic reticulum-resident protein 57 (ERp57) in the ER and the lamina propria of duodenal biopsies. (A) Electron microscopical localization of ERp57 (arrows) within intestinal lamina propria of human duodenal epithelium (CD patient, magnification × 10,200). (B) Presence of ERp57 (arrows) within the ER (labelled by PDI, arrowheads) and the cytosol of an enterocyte (NCD patient, magnification × 17,700). (C) Detection of ERp57 (arrows) within the dilated perinuclear ER (arrowheads) of RACE characterized by electron lucent cytosol (NCD patient, magnification × 17,700). (D) TG2 (arrow) within the ER (arrowhead) and at the apical membrane of an enterocyte (CD patient, magnification × 17,700). BM, basolateral membrane; Cyt, cytosol; LP, lamina propria; M, mitochondria; MV, microvilli; N, nucleus. Scale 100 nM.