Co-ordinated expression of innate immune molecules during mouse neurulation

•Expression of innate immune molecules in the developing mouse occurs prior to the formation of a functional cellular immune system.•Expression of the central complement components (C3, C5) and complement regulators (CD55, CD59, fH) occurs during neurulation.•The alternative and classical pathways are not functional due to the lack of expression of initiating factors.•The membrane attack complex is unlikely to be formed during neurulation due to lack of detectable C9 expression.•Toll-like receptors and adaptor proteins are also expressed during neurulation, whereas formyl peptide receptors are absent.