During B cell maturation,immunoglobulin genes undergo rearrangement. 1.D-->JH Rearrangement D JH Cμ Cs Cy3 Cy1 Cy2b Cy2a 5'32☒什州■■■ A section containing a number of D regions and a number of J regions loops out Cμ Cμ 5'3☒2☒□HH州 5'☒2☒HHH Excision of the loop Result:Apposition of a D and J regionDuring B cell maturation, immunoglobulin genes undergo rearrangement