English: Left panel: Gene conversion. After resection, the single-stranded 3' tail invades a homologous, intact double-stranded DNA, forming a D-loop (displacement loop). This process tolerates a limited number of imperfect sequence homologies, thus creating heteroduplex intermediates bearing mismatches (yellow circles). The invading 3'-end primes DNA synthesis, which then fills in the gaps. The cruciform junctions (Holliday junctions, HJ) migrate. Resolution (or dissolution) of HJs occurs in two different orientations (orange or red triangles), resulting in gene conversion either with or without crossing over. Middle panel: Break-induced replication (BIR). The initiation is similar to that of the previous models, but the synthesis continues over longer distances on the chromosome arms, even reaching the end of the chromosome. Here, there is neither resolution of the HR nor crossover. Right panel: Synthesis-dependent strand annealing (SDSA). Initiation is similar to that of the previous model, but the invading strand de-hybridizes and re-anneals at the other end of the injured molecule; no HJ is formed.^[1]