NATURALLY-OCCURRING, POSTNATAL CELL-DEATH IN THE CEREBRAL-CORTEX OF THE MICRENCEPHALIC RAT INDUCED BY PRENATAL X-IRRADIATION

Naturally occurring postnatal cell death in the somatosensory cortex and medial cortical areas was examined in micrencephalic rats produced after exposure to 100 cGy X-rays at embryonic day 15. The absolute numbers of dead cells per tissue section were not affected in the future subcortical white matter, but were severely decreased in the cerebral cortex when compared with age-matched controls. Furthermore, the proportion of cortical dead cells per 1000 live neurons in the cerebral cortex and the cumulative cell death across time were significantly reduced in irradiated animals. These results suggest that naturally occurring postnatal cell death in the cerebral cortex is reduced in micrencephaly.