title: The immune system in birds.
mesh_terms: D000818:Animals; D001717:Birds / Q000276:immunology*; D002060:Bursa of Fabricius / Q000276:immunology; D005260:Female; D007111:Immunity, Cellular; D007116:Immunization, Passive; D008198:Lymph Nodes / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology; D011247:Pregnancy; D013950:Thymus Gland / Q000276:immunology