<Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> Hassall's corpuscles (or thymic corpuscles (bodies)) are structures found in the medulla of the human thymus, formed from eosinophilic type VI epithelial reticular cells arranged concentrically . These concentric corpuscles are composed of a central mass, consisting of one or more granular cells, and of a capsule formed of epithelioid cells . They vary in size with diameters from 20 to more than 100μm, and tend to grow larger with age . They can be spherical or ovoid and their epithelial cells contain keratohyalin and bundles of cytoplasmic fibres . Later studies indicate that Hassall's corpuscles differentiate from medullary thymic epithelial cells after they lose autoimmune regulator (AIRE) expression . They are named for Arthur Hill Hassall, who discovered them in 1846 . </P> <P> The function of Hassall's corpuscles is currently unclear, and the absence of this structure in the murine thymus has restricted mechanistic dissection . It is known that Hassall's corpuscles are a potent source of the cytokine TSLP . In vitro, TSLP directs the maturation of dendritic cells, and increases the ability of dendritic cells to convert naive thymocytes to a Foxp3+ regulatory T cell lineage . It is unknown if this is the physiological function of Hassall's corpuscles in vivo . </P> <P> Research into the systemic organization of Hassall's corpuscles in the thymus of first - year children has determined that the corpuscles' main cells are two types of cells that differ from each other in origin, texture, function, immunohistochemical and ultrastructural features . The composition and number of accessory cells in Hassall's corpuscles depends on their stage of development . The main systemic factor of corpuscle organization is the process of synthesis, mobilization, and transduction of tissue - specific autoantigens for immune tolerance induction . </P>

What does the presence of many thymic corpuscles tell you about the thymus