title: On the phylogenetic origin of the immune system: a hypothesis.
mesh_terms: D000818:Animals; D005075:Biological Evolution; D007109:Immunity; D007448:Invertebrates / Q000276:immunology; D008954:Models, Biological; D010587:Phagocytosis; D010802:Phylogeny; D014714:Vertebrates / Q000276:immunology