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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., Competing Interests: The authors declare that there is no conflict of interest., (© 2022 Urmia University.)

The objective of this study was to highlight the postnatal development of the uterine tubes of the West African Dwarf goat from birth to 28 weeks of age by gross examination and light microscopy. There was a caudal migration of the paired uterine tubes from behind the paired kidneys at birth to the pelvic inlet at week 8 of age. Each uterine tube exhibited three segments namely; infundibulum, ampulla and isthmus. A marked flexure, the utero-tubal junction, was the point at which the uterine tubes joined the uterine horns. The length and absolute weight of the uterine tubes increased from 4.95 ± 0.28 cm and 0.02 ± 0.01 g at birth to 14.98 ± 2.79 cm and 0.22 ± 0.03 g at week 28 of age, respectively. The mucosa of the infundibulum and the ampulla showed long, branched and anastomosing primary, secondary and tertiary mucosal folds which decreased in height towards the isthmus. The mucosal folds within the isthmus were short and lacked the anastomosing pattern. The epithelia of all three segments were pseudostratified columnar. Numerous secretory blebs and extruded nuclei became apparent from week 16 of age. The thickness of the tunica muscularis varied with the segments.