MLH1 foci along the Synaptonemal Complexes (SCs) in human males and females. The spermatocyte (top) and oocyte (bottom) have been stained using antibodies against SCP3 (red), MLH1 (yellow) and, in the spermatocyte, the kinetochore (blue). Homologs 21, 13 and 18 have been identified in the oocyte, using Fluorescence in situ hybridisation (FISH) with centromere-specific probes. There are obvious differences between the spermatocyte and oocyte: the SCs are much longer in the oocyte; there are more MLH1 foci in the oocyte; MLH1 foci tend to be positioned closer to the telomeres in the spermatocyte (arrow heads). Reproduced from  and revised from .