Mice expressing Sec23a from the Sec23b locus exhibit normal pancreas histology. (A–E) In contrast to Sec23b−/− mice, Sec23bb-a/b-a mice exhibit normal (A) pancreas, (B) salivary glands, (C) nasal glands, (D) stomach, and (E) small intestine histology, similar to WT (Sec23b+/+) littermate controls. (Scale bars, 40 μm.)