An epithelial cell of the thymus. Epithelial reticular cells are pleomorphic, stellate, non-phagocytic cells which seem to be supportive in function and are held together by desmosomes. They replace the fibroblastoid reticular cells found in other lymphoid organs. Other epithelial cells in the medulla have the ultrastructure of secretory cells. Although different epithelial cells throughout the thymus appear alike by light microscopy their ultrastructure and function varies. [ GOC:tfm FMA:72208 ]