Cystic corpuscle in thymus (human, adult)

Stain: Azan. With age the remaining Hassall's corpuscles become more prominent and might represent large multiform structures of over hundreds of microns. The central cells (*) are keratinized. They might be swollen, calcify and become necrotic eventually, or undergo lysis, leaving a large cystic structure that is still surrounded by specialized flattened epithelial reticular cells (2) and their remnants. (3) thymocytes or T cells stored in the reticular spaces formed by processes of specialized epithelioreticular cells (1).