Quantitative changes in neuron and glial cells of neocortex following prenatal exposure to methylazoxymethanol.

The quantitative changes in neuron and glial cell density were analyzed in different cortical layers from frontal cortex of 3 and 12 months old mice exposed to Methylazoxymethanol (MAM) on embryonic day 15 (MAM 15) or 17 (MAM 17). An increase was found in glial cell density in all cortical layers from 3 months old MAM 17 compared to the age-matched controls. In particular, electron microscopic analysis showed that the only cells to increase in all cortical layers were the microglia cells. When the young and adult mice were compared it was noted that the glia increased significantly in all cortical layers of controls, whereas it did not change the older MAM 17. In the older MAM 15 the increase in glial density was similar to that observed in controls. No loss of cortical neurons was found between young and adult animals. In addition, the different trend of glial cell density between control and MAM 17 mice during aging was accompanied by a decline in the mean nuclear area in neurons of treated mice with respect to the controls. The hypothesis that MAM treatment seems to produce events similar to those normally occurring in aging finds support in the data of glial density and neuron size.