Histological development of the small intestinal mucosa in the ovine fetus.

Histological changes in the small intestine of 85 ovine fetuses were studied, with particular reference to the mucosa. In 24-day-old fetuses the endoderm of the intestine consisted of a single layer of epithelium. By the 26th day the epithelium was flattened and stratified. The first evidence of rudimentary villus formation was noted in 39-day-old fetuses. Intestinal glands were first observed at 56 days. Other mucosal structures were present by 101 days. At birth the intestinal mucosa was fully mature.