The presence of immunoglobulin in the bursa of Fabricius.
D000818:Animals; D002060:Bursa of Fabricius / Q000276:immunology*; D002645:Chickens / Q000276:immunology*; D008856:Microscopy, Fluorescence; D012710:Serum Albumin, Bovine; D013194:Staining and Labeling; D005719:gamma-Globulins / Q000032:analysis*
D005719:gamma-Globulins; D012710:Serum Albumin, Bovine