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Morphological changes in the late‐embryo‐stage gastrointestinal tract of Nigerian indigenous chicken were investigated using anatomical techniques. The paraffin‐embedded sections were stained with haematoxylin and eosin and periodic acid Schiff‐Alcian blue (pH 2.5) stains. During the late pre‐hatch period, the framework of the stomach was already established, but glands were yet poorly developed. Randomly oriented pre‐glandular cells in the lamina propria mucosae at embryonic day (ED) 14 became organized into elongated simple tubular glands at ED 19 and assumed adult morphology at post‐hatch day (PD) 1. Acidic and neutral mucin deposits were associated with the glandular cells. In the small intestine, enterocytes of the tunica epithelialis mucosae transformed from cuboidal‐shaped cells (at ED 14) to tall columnar cells (at PD 1). Short crypts of Lieberkühn, goblet cells, microfold cells and enteroendocrine cells were evident at ED 19, while the lamina propria mucosae and submucosa contained mesenchymal cells, reticular cells and isolated lymphoblasts. Similarly, the crypts, lymphoblasts, mesenchymal and reticular cells were also associated with the lamina propria mucosae and submucosa of the caecum and colorectum at ED 19. It was inferred from these findings that extensive cellular and tissue modifications occur in the gastrointestinal tract within the narrow window of the late pre‐hatch period. The definitive gut tunics, epithelium, glandular tissues, immune‐competent cells and tissues are formed as a result. Thus, the embryonic gut of the bird is made capable of assuming its necessary functions of food digestion, nutrient absorption, water and ion re‐absorption, immune surveillance, antibody production and immune responses at hatch. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the morphological development of the stomach of broiler chicken using histological and histo-chemical techniques. Thirty fertile eggs and 50 chicks of broiler chicken were used for the study. The results showed that at embryonic day (ED) 14, the simple tubular glands of the proventriculus were poorly defined while the framework of the compound tubular glands of the proventriculus were fully established. The secretory tubules of the compound tubular glands were lined by simple cuboidal cells at embryonic days 14, 17 and 19. However, at post-hatch days 1, 3, 7, 14, and 21, each proventricular gland contained several secretory tubules that were lined by both cuboid-shaped and columnar-shaped epithelial cells. The simple tubular glands which appeared as short tubes at ED 17, became elongated at ED 19, assuming adult morphology at post-hatch day (PD) 1. Moreover, at ED 14, poorly defined glandular areas were present in the lamina propria mucosae of the ventriculus. However, at ED 17 and ED 19, elongated pits which represented simple tubular glands were observed in the ventriculus. The production of neutral and acidic mucins in the stomach at ED 14 may reflect early secretory roles of glands in the stomach of broiler chicken. Thus, this study has provided morphological evidence of rapid development of broiler stomach glands in the late prehatch periods and maturation of the glands at hatch. These modifications may be essential for early food ingestion, food digestion and strong innate immune defense just after hatch. [ABSTRACT FROM AUTHOR]