Pro-B cell(B220ow. CD43*) DJ and v-DJ rearrangement, lga and lgp losing cd43 - Pre-B cell(expression ofsurrogate BCr) L chain v-j rearrangement immature B cell(mIgmt) negative selection mature B cell (mIgMt and mlgDf) (naive B cell) Ag, positive selection, FC/long lasting memory B cell Negative selection Positive selection clonaldeletion follicular dendritic cell clonal anergyPro-B cell (B220low, CD43+ ) DJ and V-DJ rearrangement, Ig and Ig, losing CD43 Pre-B cell (expression of surrogate BCR) L chain V-J rearrangement immature B cell (mIgM+ ) negative selection mature B cell (mIgM+ and mIgD+ ) (naïve B cell) Ag, positive selection AFC/long lasting memory B cell Negative selection Positive selection clonal deletion follicular dendritic cell clonal anergy