Lymphatic involution and early mortality in the young chicken produced by 2.2 GeV protons

Young single-comb white Leghorn cockerels were subjected to single acute doses of either 2.2 GeV protons or 250 kVp X-rays. Since young chickens exposed in the lethal range die within 48 hours of exposure, an hourly tabulation of deaths was recorded for this length of time after exposure. Animals which were exposed to sublethal doses were killed five days after exposure and their major lymphatic organs, (thymus, bursa, and spleen), removed and weighed. In the lethal range, animals exposed to 2.2 GeV protons died sooner than those receiving similar doses of X-rays, but total mortality was similar in each case at similar dose levels. The 48 hour LD sub 50 was determined to be 710 rad. Measured five days after exposure, 50% depression ED sub 50 for lymphatic organs occurred as follows: (1) thymus, 350 rad; (2) pursa, 500 rad, and (3) spleen, 450 rad. In all case R.B.E. values were not different from unity