Figure 1.

(a) Schematic of the small intestine showing its longitudinal segments. The duodenum ends at the ligament of Treitz. “x” and “y” denote the start and the end of the jejunum, respectively. “z” denotes the start of the ileum. (b) The jejunum was divided into three segments, namely proximal, medial, and distal jejunum. (c) The jejunum–ileum transition is marked by an increase in diameter of the intestine. (d) To excise explants, the jejunum was inverted, pulled up on a polydimethylsiloxane (PDMS) rod and cut at a length of ~10 mm. (e) The PDMS rod was suspended in a Transwell® insert with two diametrically opposite holes drilled through it. * denotes p ≤ .05 relative to duodenum, jejunum (x), and jejunum (y)