After puberty much of the parenchyma of the thymus, in particular cortical lymphoid tissue, is replaced by adipose tissue. The process, which is called involution , initially proceeds rapidly but slows down in adulthood. Although most pronounced in the thymus, involution is a common feature of all lymphoid tissues . Thymic corpuscles are rounded eosinophilic structures, which consist of concentrically arranged, flattened cells. Thymic corpuscles are likely to be formed by reticular cells.
Similar structures occur also in the tonsils.
Include thymic corpuscles in your drawing if you can find them. Nodes Lymph nodes are small, flattened, oval or bean shaped organs, which are situated in the course of the collecting lymph vessels. The capsule and trabeculae of lymph nodes are formed by connective tissue. Afferent lymph vessels penetrate the capsule and empty into the subcapsular space. The lymph continues thereafter through cortical and medullary sinuses towards the efferent lymph vessels , which emerge from the hilus of the lymph node .