Our group has used fetal tissue in culture to map the ontogeny of TLR4 (Leaphart et al., 2007), endoplasmic reticulum stress molecules (Afrazi et al., 2014) and TLR9 (Gribar et al., 2009), which all vary by developmental stage and contribute to NEC pathogenesis. This evidence concerns the gene TLR4 and necrotizing enterocolitis.