title: Antibody diversity in lower vertebrates--why is it so restricted?
mesh_terms: D000663:Amphibians / Q000276:immunology*; D000818:Animals; D000916:Antibody Diversity; D005075:Biological Evolution; D001717:Birds / Q000276:immunology*; D002453:Cell Cycle; D002454:Cell Differentiation; D005399:Fishes / Q000276:immunology*; D008214:Lymphocytes / Q000166:cytology; D012104:Reptiles / Q000276:immunology*