Postnatal Changes in Mice Exposed In Utero to Fast Neutrons

Abstract

Exposure to radiation during brain development stage cause microcephaly or mental retardation. Although X- and gamma-rays induced cerebral hypoplasia in rodents has been well characterized, little is known about such effects of neutrons. To examine the effects of prenatal exposure to neutrons on the development of brain and other organs, both male and female B6C3F1 mice were irradiated with fast neutrons (0.1, 0.2, 0.5, 1 Gy) or gamma-rays (0.8, 1.5 Gy) at embryonic day 13.5, and the animals were examined histopathologically 56 days after birth. Both types of radiation mainly caused hypoplasia of the cerebral cortex and lowered brain absolute weight. No sex differences were seen. These changes were remarkable in each highest dose group. The weight loss of the brain was noted at the lowest dose group of neutrons. In addition, the weight loss of the thymus, atrophy of the seminiferous tubules, and a decrease in follicles of the ovary were also noted in the higher dose groups of neutrons and gamma-rays. The degrees of these changes were larger for neutrons.