The development of the gastrointestinal system in fetal sheep in the absence of ingested fluid.

Our aim was to determine the effects of preventing the passage of ingested fluid on the development of the digestive tract in fetal sheep. The esophagus was fistulated and ligated in six fetuses at 90 days of gestation (term = 145 days); vascular catheters were implanted at day 120. Six control fetuses had vascular catheters implanted at day 120. At autopsy (day 135), although fetal body weights were similar in both groups, the abdominal girth and weights of the gastrointestinal tract, liver, and pancreas were reduced in experimental fetuses. In the gastric (abomasal) fundus and antrum, there was evidence of altered mucus composition in epithelial cells, a decrease in thickness of the muscularis externa, and an increase in thickness of the mucosa and its components. In the duodenum, there were significant changes in the thickness of most components of the wall; Brunner's glands were greatly reduced in size of were absent. Glandular cells contained less mucus in comparison to controls. In the proximal small intestine, there were significant reductions in the thickness of most components of the wall, and epithelial cell migration was retarded, resulting in a longer renewal time for villous cells. In the distal small intestine, the diameter of the intestine and submucosal and epithelial cell migration rate were significantly decreased in the experimental group. In summary, the absence of the passage of ingested fluid in fetal sheep restricts the growth and development of the gastrointestinal tract, liver, and pancreas.