title: Early development of the avian immune system.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D001717:Birds / Q000254:growth & development / Q000276:immunology*; D002060:Bursa of Fabricius / Q000276:immunology; D002454:Cell Differentiation; D005260:Female; D007109:Immunity; D007110:Immunity, Active; D007111:Immunity, Cellular; D008214:Lymphocytes / Q000276:immunology; D008221:Lymphoid Tissue / Q000276:immunology; D010063:Ovum / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D013950:Thymus Gland / Q000276:immunology; D015017:Yolk Sac / Q000276:immunology