A prospective study of prenatal and postnatal development of thymus of Deshi chicken

Thymus was one of the primary lymphoid organs along with the bursa in birds. The growth of the thymus of deshi chicken (Gallus Domesticus) from prenatal embryonic day fifteen (ED15) to postnatal day ninety (D90) were studied. In macroscopic study, it was found as a paired, lobulated gland, one half of which was located on either side of the neck. Each half consists of six to eight, flattened, ovoid to elongated, pale white to yellowish white lobes of varing size and shape of lymphoid tissue lying in the sub-dermal connective tissue of the neck. Histologically, the thymus of deshi chicken at embryonic day fifteen was covered by a very thin connective tissue capsule from which septa arises and divides the gland into lobes and lobules. The lobules were homogenous, small in size and the cortex and medulla were demarcated. Lobules have developing Hassall's corpuscles and they were of uniform shape and size. The lobules become well developed with advancing age. The cortex gradually becomes thicker and was packed with large lymphocytes. Hassall's corpuscles became larger and there number increases at postnatal period (D90) in the medulla of the thymus. The growth and development of thymus at each stage of the study period were found to be significantly high. The present finding of thymus of deshi chicken was found similar to the adult hybrid chicken. The study also indicates that the chicken thymic cell population, structure & functions was similar to the human thymus histologically. It was also found that the chicken embryo allows easy experimental access to all the stages of the thymic development so the present study will be helpful for experimentation on lymphoid organs and to understand pathophysiology of immunological diseases of human.