Molecular evidence for BCL2-induced rescue of FLT3L and IL-7Rα–dependent thymopoiesis in Flt3l^−/−Il7r^−/− mice. (A) Ethidium bromide-stained agarose gels with resulting PCR products from RT-PCR analysis of Rag2, Ptcra, Lck, and Il7r message in thymus from mice of the indicated genotypes. Autoradiograms of (B) Tcrb-D₁-J rearrangements and (C) Tcrb-V-DJ rearrangements in the thymus of WT, BCL2, Flt3l^−/−Il7r^−/−, and Flt3l^−/−Il7r^−/−BCL2 mice. Amplification of a region in the Gata1 gene was performed to verify that the DNA preparations were of comparable quality. Results are from representative mice of each genotype. Arrows indicate rearrangement products. Please note that lines visible on reproduction of gels represent reproduction artifacts.