Biological roles of the meiotic HORMADs. Model for meiotic HORMAD assembly/disassembly at the meiotic chromosome axis. In early meiotic prophase (top), HORMADs are likely recruited to chromosomes through closure motifs in cohesin/SC proteins (pink), then self-assemble through HORMA–closure motif interactions. On chromosomes, HORMADs promote DSB and CO formation through largely unknown mechanisms. Coinciding with the maturation of COs and SC assembly in late prophase (bottom), HORMADs are removed from the chromosomes in a TRIP13-dependent manner, downregulating further DSB and CO formation.