Morphology and histology of the thymus gland in dromedary camel with particular reference to thymic Hassall's corpuscles

Abstract

The thymus gland is the primary lymphoid organ that undergoes postnatal growth followed by gradual atrophies and functional decline with age progress. The thymus gland has similar morphology across species, with a thoracic portion in the cranial mediastinum and a cervical portion along the trachea. Histologically, the thymus consists of an outer cortex populated with darkly stained T lymphocytes and a pale inner medulla. The medulla contains thymic Hassall's corpuscles (THC), which may function as sites for T cell maturation or as communication points between T cells and antigen-presenting cells. The thymus gland in camels has yet to be well studied, with limited research on its macroscopic and microscopic anatomy. In this study, the thymus glands of camel calves were examined. The thoracic portion was triangular and located in the cranioventral part of the mediastinum. The cervical portion extends cranially to the level of the thyroid gland and, in some cases, to the larynx. Histologically, the camel thymus had a fibrous capsule and connective tissue trabeculae, dividing the gland into incomplete lobules. The cortex was heavily populated with thymocytes, while the medulla contained epithelial reticular cells. A perivascular space (PVS) consisting of mature T lymphocytes surrounding blood vessels was also identified. THCs were present in the medulla, with variable shapes and forms ranging from small-sized to very large-sized with degenerative changes. Further research is needed to fully understand the role of the thymus gland in camels and its implications for vaccination programs and immune health.

Keywords

• anatomy
• histology
• lobule
• cortex
• medulla