We report a molecular analysis of the chicken Ig loci in single bursal follicles from 3- to 7-week-old chickens. Each follicle contained between 10(5) and 3 X 10(5) cells. The Ig gene rearrangement patterns obtained were compared to the pattern observed with the corresponding total bursal DNA. The results obtained for the light chain locus imply that a very small number (two on average) of rear...