Hassall's corpuscles are located in which organ?

• A. Thymus
• B. Spleen
• C. Lymph node
• D. Bone marrow

Answer: (A)

Hassall's corpuscles are histologic features of the thymus, located in the medulla. They are concentric, whorled aggregates of epithelial reticular cells that often keratinize, giving eosinophilic, circular structures. Their presence helps identify thymic tissue under the microscope. The thymus is the site of T cell maturation, with the cortex rich in developing thymocytes and the medulla housing fewer cells and these distinctive corpuscles. They are not found in spleen, lymph node, or bone marrow, which lack this medullary structure. While their exact function is not fully clear, they’re thought to play a role in shaping the T cell repertoire, possibly influencing regulatory T cell development.