Fig. 1. (A) Coexistence of two types of -H2AX foci on surface-spread preparations of rodent spermatocytes. -H2AX foci were revealed by fluorescein-conjugated secondary antibodies (green). Axial elements and SCs were labeled by anti-SCP3 antibody using a Cy3-conjugated secondary antibody (red). In mice, numerous S-foci (arrowhead) and L-foci (arrow) coexist at early zygotene (a). At early pachytene (b), numerous S-foci persist and only few L-foci are detected. At late pachytene (e), the number of S-foci strongly decreased whereas the number of L-foci remained steady. Finally, at diplotene (f) no more S-foci were found. Numerous S-foci were also detected on early pachytene of guinea pig (c) and chinchilla (d) (see Table 1 for quantification of S-foci number). From pachytene to diplotene stages the XY body was intensely stained (^*). Bars, 10 µm. (B) Distinct -H2AX L-foci distributions at early and late pachytene, diplotene and diakinesis. Pachytene cells at early (black bars) and late (dark gray bars) stages, diplotene stage (light gray bars) and diakinesis (white bars) were distributed according to their number of L-foci per cell.