Why mMT Mice Don't Have B Cells

For Sara and Susan. mMT mice do not have B cells because the membrane exon of the mu heavy chain has been disrupted. Targeted disruption of this exon results in failure to make productive rearrangements and thus death of the developing B cell. Basically, in order for a pre-B cell to survive it has to make cytoplasmic m. If this doesn't happen the pre-B cell dies so you never get any mature B cells and thus no antibody production.