Development of the bovine duodenum with reference to enterochromaffin cells

The present light microscopic study describes the morphological changes which occur in the duodenal mucosa of the bovine fetus from the third month of gestation until birth with regard to the sequence of appearance and morphology of enterochromaffin cells. The mucosa of the duodenum is prepared for digestive activity during the first months of development. This becomes obvious in the early differentiation of the fetal intestinal mucosa. The enterocytes in villus epithelium contain glycogen in the early months. These glycogen pools seem to shrink during the following months. They may provide a metabolic reserve for the fetus, which derives all of its nutrition from carbohydrates. Enterochromaffin cells appear in the three month old bovine fetus with two cell-types situated in the epithelial lining of crypts and villi. The density of enterochromaffin cells increases during gestation. There were no findings to indicate that the fetal enterochromaffin cells did not originate from endoderm. The early appearance from enterochromaffin cells (which are the producers of serotonin, 5-hydroxytryptamine) correlates with first gastrointestinal movements, which are known to commence in the first third of gestation, leading us to believe that 5-HT represents the chemical inducer of muscular motility in the developing intestine.