Lymphoid Tissues in Radiation Chimeras

The purpose of this study is to analyse the mechanism of achievement and maintenance of radiation chimerism. Inbred DA and PVG/c strain rats were thymectomized when 4 to 6 weeks old. Four to 8 weeks later they were lethally irradiated with 800 to 1000 R and shortly thereafter injected intravenously with 5-15×10^8 viable bone marrow cells from (PVG/c×DA)F_1 hybrid. These rats were then grafted with (PVG/c×DA)F_1 hybrid skin (Fig. 1). 19 out of 23 DA and 20 out of 36 PVG/c rats protected with (PVG/c×DA)F_1 bone marrow cells survived for more than 60 days without rejecting the skin graft (Table 1). Such rats will be referred to as semiallogeneic radiation chimeras (Fig 3)…