Proliferation of injected lymph node and thymus cells in lethally irradiated mice.

chromosome were injected. together with chromosomally unmarked bone marrow, into lethally irradiated mice. Mice were sacrificed at intervals and the dividing cells in the bone marrow. spleen. thymus. and mesenteric lymph node were examined cytologically. It was found that cells derived from lymph nodes and thymus proliferated in the lymph node of the irradiated recipient and to a much smaller extent in the spleen; only exceptionally were they seen in the bone marrow or thymus. No evidence was obtained to suggest that lymph nodes and thymus normally contain any stem cell capable of differentiating into granulopoietic and erythropoietic cells. (auth)