Single-End Invasion (SEI)

A meiotic recombination intermediate during the transition from double-strand breaks to double-Holliday junction. SEIs are formed by strand exchange between one and then the other double strand. The appearance of SEI coincides with that of the synaptonemal complex. SEI is preceded by a nascent double-strand partner intermediate that differentiates into a crossover and a non-crossover type after the synaptonemal complex has formed. Strand exchange occurs relatively late after synapsis and recombination may be avoided between homeologous and structurally rearranged partners. Holliday model, synaptonemal complex, homeologous; Hunter N, Kleckner N 2001 Cell 106:59.