Morphological features of the late-embryo-stage gastrointestinal tract of free-roaming light ecotype Nigerian indigenous chicken.

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.

Pre-hatch and post-hatch development of the bursa of Fabricius in broiler chicken: a morphological study.

The developmental morphology of the bursa of Fabricius (BF) of broiler chicken was evaluated in this study using gross anatomical, histological, reticulin histo-chemical, and transmission electron microscopic techniques. The result showed that the short plica of the BF at embryonic day (ED) 14 was a mesenchymal tissue that contained cells, including mesenchymal cells and lymphoblasts. The organo-somatic index (OSI) of the BF peaked at ED 17, while the BF of ED 19 showed well delineated follicle-associated and inter-follicular epithelial (IFE) cells. Whereas, the IFE contained apical vacuoles which increased in size with age, the BF contained lymphoid follicles which were first observed at ED 17, and increased steadily in mean diameter from ED 19 to post-hatch day (PD) 28. The framework of the inter-follicular areas and the follicular capsules were composed of collagen type III fibres. Moreover, the cortico-medullary basement membranes were well established with peripheral and cortico-medullary basement capillaries becoming very consistent between PDs 5 and 7. The lymphoid follicle contained lymphocytes with mitotic figures, and plasma cells which showed extensive network of rough endoplasmic reticulum at PD 21, while macrophages contained increasing evidence of phagocytosis from PDs 35 to 56. In conclusion, the morphological features of the BF of broiler chicken in this study reveals that the key function of B-cell maturation within the BF may occur between the first 3 to 4 weeks after hatching, and thereafter, may primarily produce immunoglobulins until involution occurs.

Light and transmission electron microscopic evaluation of the lamina epithelialis mucosae in the ileum of pre- and post-hatch broiler chicken.

Morphological development of the lamina epithelialis mucosae (LEM) of the ileum of broiler chicken was evaluated using light and transmission electron microscopic techniques. Ileal sections were collected on embryonic days (ED) 14, 17 and 19, as well as post-hatch days (PD) 1, 3, 5, 7, 14, 21, 28, 35, 42 and 56. The result showed that the ileal LEM, which were poorly defined at embryonic days 14 and 17, consisted of enterocytes and some atypically shaped goblet cells. Apico-lateral tight junctions and irregularly shaped microvilli were associated with the enterocytes at ED 14 and 17. The enterocyte microvilli were more uniform in shape and distribution at ED 19. The embryonic goblet cells were varied in shape and possessed basally displaced, star-shaped nuclei and small apical cytoplasmic vacuoles. During the post-hatch ages, the LEM was a typical epithelium with a single layer of columnar-shaped enterocytes that became highly elongated at post-hatch day (PD) 7. The goblet cells were characteristically 'wine-glass' shaped. Follicle-associated epithelium (FAE) showing numerous lymphocytes among the enterocytes occurred in the post-hatch LEM. The intra-epithelial lymphocytes (IEL) were first encountered at PD 1, but increased several folds within the first two weeks post-hatch. Entero-endocrine cells were observed in the epithelium from PD 21. Finally, from this study, it is obvious that enterocytes and small atypically shaped goblet cells occur in the ileal LEM during the pre-hatch period, but these cells assume adult morphological characteristics after hatch. Thus, the cells of the ileal LEM play strategic absorptive, secretory and protective roles in the gut.

Assessment of age-related morphological changes in the testes of post-hatch light ecotype Nigerian indigenous chicken.

The age-related morphological changes of the testes in light ecotype Nigerian indigenous chicken were evaluated in this study using gross anatomical, histological and histomorphometric techniques. The results showed that the testes of 3- to 9-month-old birds were light pink while testes of sexually mature chicken were creamy white in colour. The left and right testicular weight, length, diameter, circumference and the organosomatic indices increased significantly (p < .05) with increasing age across the groups. Although the mean tubular diameter and epithelial height of the left and right seminiferous tubules increased significantly (p < .05) with age, the tubular diameter, epithelial height and luminal diameter did not vary significantly (p > .05) between the left and right testes of all the groups. The one-cell layer thick germinal epithelium of the left testes at 3 to 6 months old showed islands of cell proliferation that contained spermatogonia and spermatocytes. At 6 to 9 months, the left testes exhibited numerous early spermatids with occasional occurrence of late stage spermatids while the right testes showed scanty early stage spermatids. At 12 to 18 months, the germinal epithelia of both left and right testes were characterized by the presence of Sertoli cells, spermatogonia, primary spermatocytes, numerous early and late stage spermatids as well as spermatozoa. In conclusion, the morphological features highlighted in the present study show that at pre-pubertal periods, the left testes may develop faster than the right testes. However, both left and right testes may participate actively in the production of spermatozoa during the post-pubertal life.