Electron Microscope Observations on Tingible Body Macrophages in Mouse Spleen

It is generally accepted that the tingible bodies (Körper) of Flemming (7) found in lymphatic tissue germinal centers represent phagocytized nuclear debris of small lymphocytes (1, 2, 6, 7, 11, and others) or both lymphocyte and erythrocyte debris (15) . Several ideas about the significance of tingible bodies assume that they are small lymphocytes . The "graveyard theory" emphasizes the phagocytosis of pyknotic small lymphocytes (6, 9, 11) . This theory was extended by Hamilton (8), Trowell (17), and Sundberg (16) who postulated reutilization of small lymphocytes in lymphocytopoiesis . Andrew (1) stressed the role of degeneration and phagocytosis of small lymphocytes in germinal centers as indicating that these centers are not germinal but reactive, as proposed by Hellman (10) . Recently, Ortega and Mellors (13) suggested that intrinsic germinal center cells degenerated after secreting gamma globulin and were phagocytized by tingible body macrophages . The identification of tingible bodies as small lymphocytes rests on indirect evidence since stained nuclear debris viewed in the light micro-