1. The function and structure of dog ileal mucosa was examined immediately after arterial ischaemia for 1 h and 1, 3 or 7 days after the trauma.
2. Immediately after the ischaemia, there was a net movement of water and ions into a luminal perfusate in vivo. One day later, there was no net movement of water and electrolytes but net absorption returned on the third day.
3. Active transport of phenylalanine or β-methylglucoside by mucosal strips in vitro was abolished immediately after the trauma but was largely restored 1 day later. There was a close correlation between glucose absorption in vivo and β-methylglucoside uptake in vitro.
4. Morphological study revealed pronounced desquamation of enterocytes immediately after the trauma. The regenerating mucosa had shorter villi and crypts, and lower enzyme activities assessed histochemically 1 day later. Most parameters had returned to normal by the third post-operative day.