Architecture of blood vessels in human fetal gastric corpus: a corrosion casting study

Vascular architecture of the gastric corpus was investigated in 16-24 wk hu man fetuses using a corrosion casting technique and the scanning electron m icroscopy. The general distribution of blood vessels seen in adults has alr eady been established in the fetus, with three major vascular plexuses loca ted in the serosa, submucosa and mucosa. The serosal plexus, supplied and d rained by large extramural vessels, contained anastomosing, arcade-like arr ays of arteries and veins with their branches piercing the muscularis and c ommunicating with the compact submucosal plexus. Vertical arterioles and ca pillaries were sent by submucosal arteries to supply a very dense capillary plexus which surrounded the gastric pits and consisted of wide, sinusoidal vessels showing morphological manifestations of angiogenesis by intussusce ptive growth. The plexus was drained by vertical venules emptying into subm ucosal veins. In contrast to the richly vascularized upper half of the muco sa, the lower half showed a relative paucity of blood vessels, probably due to the thinness of the fetal mucose allowing an effective diffusion of oxy gen and nutrients from the upper half. Neither arteriovenous anastomoses, n or end-arteries were found in the fetal stomach. Results of this study supp ort one of the two existing models of mucosal vascularization in the human stomach: i. e, the model postulating the presence of short and long arterio les and two distinct, albeit interconnected capillary networks in the upper and lower zones of the mucosa respectively. In human fetuses, the latter n etwork is absent; it probably develops by remodelling of the preexisting ve rtical capillaries in the last phase of pregnancy, prior to the onset of ga stric gland function.