Thymic, bursal and lymphoreticular evolution.
D000663:Amphibians / Q000033:anatomy & histology / Q000276:immunology; D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000033:anatomy & histology / Q000276:immunology; D001854:Bone Marrow Cells; D002060:Bursa of Fabricius / Q000033:anatomy & histology; D005399:Fishes / Q000033:anatomy & histology / Q000276:immunology; D006410:Hematopoiesis; D006801:Humans; D008198:Lymph Nodes / Q000033:anatomy & histology; D008221:Lymphoid Tissue / Q000033:anatomy & histology / Q000276:immunology*; D051381:Rats; D013154:Spleen / Q000033:anatomy & histology; D013950:Thymus Gland / Q000033:anatomy & histology