Formation of the astroglia in the mouse neocortex after temporary prenatal blockade of serotonin synthesis.

The dynamics of the appearance of astrocytes in the mouse neocortex after prenatal blockade of serotonin synthesis was studied. Experiments were performed on F1(CBA/C57Bl) hybrid mice. Serotonin release was suppressed with parachlorophenylalanine, given as single doses to mothers during the early postimplantation stage of pregnancy. Astrocytes differentiating in the brain were visualized by an immunohistochemical method for detecting astrocyte intermediate filament protein, this being a specific glial fibrillary acidic protein (GFAP) allowing not only marking of cells, but also assessment of the presence, extent, and rate of cell differentiation. The results showed that in normal conditions, GFAP-positive cells appeared in layer I of all neocortical areas during the first week after birth, i.e., the area cingularis, the area occipitalis, the area parietalis, the area insularis, the area praepiriformis, the area piriformis, the area entorhinalis, and the area subiculum. The process of astrocyte differentiation intensified with development. Barrier structures also formed. During the first days of postnatal development, astrocytes and their processes appeared around vessels and the walls of the lateral ventricles. The neocortex of rats developing in conditions of blockade of serotonin synthesis showed smaller numbers of GFAP-positive cells, particularly in the white matter, at all stages of postnatal development studied.