Univalents were also seen, varying in number from one to nine (3.0 ± 2.4 on average). In many cells odd numbers of univalents were found, indicating that some of their partners were involved in non-homologous synapsis in a multivalent. For the same reason the average number of observed trivalents was lower than the expected four (2.5 ± 1.4 on average). The number of bivalents in oocytes was lower than the expected 19 (15.4 ± 1.5 on average), again due to involvement of one or both partners in non-homologous synapsis in multivalents. Asynapsis was frequently observed around pairing partner switch points and at the ends of multivalent chains. Unpaired regions were labeled with γH2A.X (Fig. 4a,b, Fig. S2) and RAD51 (Fig. 4c,d, Fig. S2), indicating that they contained unrepaired DSBs.