Haemopoiesis in the Beagle Foetus afterin UteroIrradiation

Abstract

On day 33 of gestation, foetal beagles were irradiated in utero (0.9 Gy of 60Co gamma-irradiation, 0.4 Gy/min). Foetal haematocytopoiesis was studied during the third trimester of gestation (days 42-55). Peripheral blood nucleated cell counts were 33 per cent lower than normal on day 44 and continued to be lower until day 49, when values became higher than normal. Splenic cellularities of irradiated pups on day 44 were more than 3 times those of the nonirradiated, but thereafter they were similar to normal. Differences in haemopoietic progenitor cell activity between irradiated and normal foetuses were observed. In comparison with the other foetal tissues, the foetal liver appeared to experience greater radiation injury. For example, on day 44, the irradiated liver BFU-E, CFU-E, and GM-CFC per 10(5) cells were almost fivefold lower than normal values. Spleens of irradiated foetal beagles contained a marked increase in all haemopoietic progenitor cells (BFU-E, CFU-E, and GM-CFC) and recognizable proliferative granulocytic cells and nucleated erythroid cells. The haemopoietic activity of the irradiated bone marrow during days 42-44 was similar to that of the irradiated spleen, and compensated for the damaged liver. However, unlike the irradiated spleen, the irradiated bone marrow had decreased BFU-E activity compared with the values for the nonirradiated bone marrow during days 48-55. Until day 50, the irradiated marrow contained fewer recognizable proliferative granulocytic cells but more nucleated erythroid cells.

Contralateral response of macrophages and astrocytes to injury in the cerebral hemisphere of 6‐day‐old rat following prenatal gamma irradiation

“…The whole-body irradiation at different stages of prenatal development affected also populations of haemopoietic cells located in different organs and having different recovery abilities (Koshimoto et al, 1994;Morris et al, 1991;Weinberg, 1983). This should result in different long-term functional impairments of the system both in developing and adult individuals (Gidali et al, 1985;Grande and Bueren, 1995;Nothdurft et al, 1984;Weinberg, 1983;Weinberg et al, 1983).…”

“…In the present study, exposure to gamma radiation at different stages of prenatal development affected different populations of haemopoietic cells located in different organs (Koshimoto et al, 1994;Morris et al, 1991). It interrupted ontogenesis of the mononuclear phagocyte system which is an exogenous source of microglia/macrophages acting in the nervous tissue following injury (Gidali et al, 1985;Grande and Bueren, 1995;Nothdurft et al, 1984;Weinberg, 1983;Weinberg et al, 1983). The recruitment of macrophages to the lesion site and their proliferation might, therefore, be modified in a way dependent on the stage of prenatal development at which the irradiation was performed.…”

Haematology of foetal sheep

“…Many workers have reported similar observations in other foetal species. 40,41 Unlike in humans, 42 bone marrow in foetal sheep does not support any major lymphopoietic activity.…”