Hassal corpuscles are seen in:

Ref: Grays Anatomy 40th Ed Pg 939Explanation:Hassall's corpusclesThese are whorls of flattened, concentrically layered medullary epithelial cells, and are characteristic features of the thymic medulla .They start to form before birth and their numbers increase throughout life.Their function is not clear, although they may represent a site for removal of dying, apoptotic thymocytes, because their centres are eosinophilic, partly keratinized and often contain cellular debris.