Morphologic alterations in rat bone marrow and spleen after neutron and gamma irradiation.

Morphologic alterations were studied in rat bone marrow and spleen after wholebody neutron irradiation (2 Gy dose). Neutron irradiation causes damage of hemapoietic organs changing their morphological structure already in the first hours after irradiation. The damage is further intensified reaching its maximum on 3rd day. Recovery of the hemopoiesis in the bone marrow and spleen begins approximately on 5th day being complete by 15th to 21st day after irradiation. Continuous gamma irradiation for 10.5 days following single neutron irradiation (total accumulated dose of 6 Gy, daily input dose of 0.574 Gy) results in prolonged inhibition of the hemopoietic activity until termination of the irradiation. Reparation of the damaged bone marrow is seen only on about day 5 after cessation of continuous irradiation; this implies that continuous irradiation following neutron irradiation delays the onset of reparative processes by approximately 5 days. In the spleen reparation of erythropoiesis begins already during the irradiation.