Widely used adaptation of rat HHF model with vast number of variations that often include exposure to bacterial pathogens (Klebsiella, C. sakazakii, E. coli, “NECteria”) ± LPS for increased disease manifestation. Commonly applied NEC induction protocol in transgenic mice testing specific genes/mechanisms (TLR4, VEGF, eNOS) ± exposure to various reagents/antibodies/modulators (amniotic fluid, HIF1α, IGF) to test therapeutic potential. This evidence concerns the gene TLR4 and necrotizing enterocolitis.