MUCOSAL MORPHOGENESIS AND CYTODIFFERENTIATION IN FETAL PORCINE SMALL-INTESTINE

Background: Development of the small intestine is essential for proper nutrition of the fetus and the neonate, This investigation examines t he morphogenesis and cytodifferentiation of developing fetal porcine s mall intestinal mucosa. Methods: Fetuses were collected from gilts aft er hysterectomy. Small intestinal segments were removed and processed for light and electron microscopy. Results: Fetal porcine small intest ine developed from a simple tube of stratified epithelium to a tube co ntaining villus and intervillus regions of simple columnar epithelium, This development occurred in a proximal to distal direction. By Day 4 0 of gestation, cytodifferentiation was evident with the presence of g oblet cells and enteroendocrine cells in the duodenum, As development progressed, microvilli lengthened and components of the apical endocyt ic complex (AEC) were observed, By Day 110 of gestation, tubular and v esicular components of the AFC were confined to the jejunum, whereas l arge lysosomal vacuoles were observed in the distal jejunum, Duodenal epithelium at Day 110 was similar to postnatal epithelium. Conclusions : The pattern of fetal porcine small intestinal development is similar to that reported for fetal human small intestine. Villus development and cytodifferentiation occur at similar relative times in gestation w hen compared to the human. These observations support the use of the f etal pig as a model for investigations of human small intestinal devel opment. (C) 1997 Wiley-Liss, Inc.