Piglets are vulnerable to stress during weaning because of changes in the feeding environment, nutrients, and other growth-impacting conditions. In this study, stress injury was modelled by continuous intraperitoneal injection of lipopolysaccharide (LPS) and was used to investigate the dynamics of antioxidant indices and immunoinflammatory factors in the piglet thymus.

The study designed to investigates the anatomical and histological structures of the thymus gland in broiler chick embryos.  Ten healthy, normal embryos at 12th and 20th days old chick embryos was used, divided into five embryos for each age. The thymus was well developed at 12th day chick embryo, Anatomically consisted of 6-8 lobes which are similar in both sides .small, translucent bean shaped lobes that became pale in color at 20th day old embryo, these lobes located in both sides of the neck, positioned parallel to the jugular vein and vagus nerve.               Histological structures of thymus gland were composed of capsule, cortex and medulla.  At 12th day old of chick embryo the thymus was surrounded by a thin connective tissue capsule, which septa extends into the gland stroma to form a lobulation for each lobe, the cortex and medulla was not differentiated at this age. At 20th day old chicks embryo, the lobules start to recognize and composed of external dark stained cortex with a high population of lymphocytes and internal light stained medulla with less abundant of lymphocytes , reticular fiber and epithelial reticular cells with the appearance of Hassall's corpuscles.

Objectives: Avian lymphatic system plays a very significant role in immunity as well as disease control. This research aimed to investigate the histomorphological changes and involution of the thymus of Sonali chicken at different post-natal stages in Bangladesh as the age-related changes of the thymus of Sonali chicken were not described before. Materials and methods: A gross and microscopic investigation was performed on the thymus of 25 healthy Sonali chickens representing different stages of post-natal life: days 1, 14, 28, 42, and 56. Experimental chickens were sacrificed by cervical subluxation, and the thymus was collected and subjected for both the gross and histological studies. The histological changes were examined with light microscopy after H&E staining. Results: The thymus was located in close association of the jugular vein, having a long chain of thy¬mic lobes, 58 lobes on each side. The statistically significant age-related changes were observed (p < 0.05). All gross parameters (weight, length, width, and thickness) found to be increased up to day 42. On day 56, the growth was found to decline from the previous groups. The microscopic observations revealed the same pattern of changes such as gross parameters, i.e., continuously increased till day 42 and then declined (p < 0.05). At day 56, the involutory signs such as partial loss of interlobular septa and accumulation of adipose tissue in connective tissue septa were found. Conclusion: It is well known that in chicken, after a certain period, the thymus got involuted. In Sonali chicken of Bangladesh, the age of involution was notified at day 56/8th week of the post-natal stage, which was correlated both in macro- and microscopic observations. [J Adv Vet Anim Res 2020; 7(2.000): 324-330]