Histological Study of Small Intestine Development in Local Chicken (Gallus gallus domesticus) and Duck (Anas platyrhynchos domesticus) Embryos

Growth of the avian small intestine initiates during embryogenesis through simultaneous and compound histogenesis proceedings. The histological study of the small intestine development in local chicken and duck embryos followed a protocol of paraffin embedding technique, and the tissues were stained by Hematoxylin and Eosin stain. The histological study was divided into three age periods, which showed that the walls of the three parts of the small intestine were similar with some differences. The first period in chickens showed that the mucosa had small folds, while the duck had very close folds. The second period in chickens showed that the villi had equal height and width with an elongated columnar epithelium and the presence of Paneth cells; tunica muscularis consisted of two thin muscular layers, the middle circular and outer longitudinal, interspersed with Auerbachian plexuses and tunica serosa consisted of mesothelial cells. While in the duck, the folds’ epithelium had a brush border, interspersed with goblet cells, and the presence of Auerbachian plexuses between the middle and outer layer of muscularis. At the end of the second period in chickens, the duodenal mucosa contained finger-shaped villi, while in ducks, the submucosa contained the Meissner plexuses, which were elongated oval in chickens and circular in ducks, and there were no Brunner glands in both bird types. The jejunum’s villi were finger-shaped with equal length but shorter than the duodenum’s villi, and there were plicae in its wall. The intestinal crypts formed in two ways: either from undifferentiated embryonic cells or by dividing the crypt into two by bifurcation. The ileum’s villi were shorter and wider in chickens, while in ducks, they were hook-shaped, with the presence of Beyer’s batches. The third period in chicken and duck arrangements an efficient small intestine by the completion of embryogenesis. In conclusion, this combined examination offers a roadmap for researchers to estimate varied investigational data that have gotten at the histogenesis of small intestine growth within the two bird types.