Flying vertebrates (birds and bats) are under selective pressure to reduce the size of the gut and the mass of the digesta it carries. Compared with similar-sized nonflying mammals, birds and bats have smaller intestines and shorter retention times. We review evidence that birds and bats have lower spare digestive capacity and partially compensate for smaller intestines with increased paracellu...

Crohn’s disease commonly affects the small and large intestines. Its symptoms include ulcers and intestinal stenosis, and its diagnosis is currently performed using an endoscope. However, because the endoscope cannot pass through the stenosed parts of the intestines, diagnosis of the entire intestines is difficult. A CT image-based method is expected to become an alternative way for the diagnos...

BACKGROUND The small intestine is constructed of many crypts and villi, and mouse studies suggest that each crypt contains multiple stem cells. Very little is known about human small intestines because mouse fate mapping strategies are impractical in humans. However, it is theoretically possible that stem cell histories are inherently written within their genomes. Genomes appear to record histo...