Abstract
It is well known that radiation induces microcephaly or mental retardation when fetus is irradiated during brain development stage. Several researches have demonstrated that prenatal irradiation of low-LET radiation induced cerebral hypoplasia in rodents. However, little is known about neutrons. So, we examined the effects of prenatal exposure of neutrons on mice brains. B6C3F1 mice were irradiated with fast neutrons (0.1 to 1Gy) or gamma-rays (0.8, 1.5Gy) on embryonic day 13.5. At 8 weeks of age, offsprings of both sexes were necropsied. The brains were removed, weighed, and then were fixed in formalin for histopathology. Both types of radiation caused hypoplasia of cerebral cortex and brain absolute weight loss. These changes were remarkable at the highest dose groups. The brain weight loss was still noted at 0.1Gy of neutrons. Histopathologically, loss of cortical neurons were observed. The degrees of these changes were larger for neutrons, the RBE for brain weight loss was 2 to 3 for both sexes. [J Radiat Res 44:407 (2003)]
