Expression of macrophage colony-stimulating factor gene in the mouse brain during development.

We have investigated the expression of macrophage-colony stimulating factor (M-CSF) gene in mouse brain during development. Northern blot analysis of cerebral RNA evidenced a 4.5-kb M-CSF transcript from day 14 of gestation until 2 weeks after birth. The cell type responsible for this transcription was studied using in vitro cell cultures. The 4.5-kb M-CSF transcript was found both in astrocyte primary cultures and in immortalized astrocytic cell lines. M-CSF mRNA was also detected in lipopolysaccharide-stimulated brain macrophage cultures. These results suggest that M-CSF is involved in the outgrowth of microglia during ontogenesis.