Early effects of low doses of ionizing radiation on the fetal cerebral cortex in rats.
Pregnant rats were exposed to gamma radiation from a 137Cs irradiator on gestational Day 15. Fetuses that received 0.25, 0.5, 0.75, or 1.0 Gy were examined 24 h after irradiation for changes in the cells of the cerebral mantle of the developing brain. The extent of changes following 0.5 Gy was studied at 3, 6, 12, or 24 h after exposure. Cortical thickness of the cerebral mantle was not significantly altered. The number of pyknotic cells, number of macrophages, nuclear area, and number of mitotic cells were altered in a dose-related way. The number of pyknotic cells was significantly increased at all doses. A positive correlation between the number of pyknotic cells and the number of macrophages developed with time. At 3 h after irradiation about 60% of pyknotic cells were found in the subventricular zone and about 25% in the intermediate zone and cortical plate. The number of such cells in the upper layers of the cortex steadily increased up to 24 h, at which time about 70% of pyknotic cells were in these two layers. The relationship of the movement of pyknotic cells to migration of postmitotic neuroblasts is discussed.
Norton
S
S
University of Kansas Medical Center, Kansas City 66103.
Kimler
B F
BF
D000818:Animals; D002540:Cerebral Cortex / Q000196:embryology / Q000473:pathology / Q000528:radiation effects*; D005260:Female; D005333:Fetus / Q000528:radiation effects*; D011247:Pregnancy; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors