Cell death and cell number in the developing cerebral cortex of MAM treated mice.

The postnatal cell death decline in microencephalic mice produced after methylazoxymethanol-acetate injection during embryonic development may adjust the final cell number of treated animals in the mature neocortex. Quantitative observations of cortical cell number in normal and treated mice, from 5 days to adult age were carried out. The proportion of cortical dead cells per 1000 live cells in a standardized cortical column and the cumulative cell death across time were studied in mice aged 5-10-20-30 days. Two main results were obtained. First, the mature neocortex of treated animals shows a number of cells which is significantly lower with respect to the controls but the difference is less accentuated than in the developing neocortex. Secondly, the proportion of cortical dead cells per 1000 live cells at every date studied and the cumulative cell death across time decreased in cerebral cortex of treated mice when compared with age-matched controls. Our data show that decreasing initial cell number by prenatal MAM injection is correlated to an increase in the survival of cortical cells.