Expression of four cytokine genes, transforming growth factor (TGF)β2, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and macrophage colony-stimulating factor (CSF-1 also known as M-CSF) was examined to determine whether these genes are developmentally regulated in the brain. Northern blots were performed on RNA isolated from the mouse brain from embryonic day 15 (E15) through postnatal day 9. TGFβ2, gene expression was relatively high in the earliest embryos studied and decreased after E16-E17, and the three transcripts were developmentally regulated. TNF-αand IL-6 were detected in total RNA on all days studied. CSF-1 was detected only in polyadenylated RNA. The data suggest that expression of these cytokines is related to specific developmental events that share cellular functions with regenerative or inflammatory processes.