Evidence for reduced cytological interference in Spo11+/?Atm?/? spermatocytes.

Pachytene spermatocyte spreads were immunostained for SYCP3 and MLH1. For autosomal bivalents with two or more MLH1 foci, distances between the foci were measured and expressed as absolute distance (��m of SC) or relative distance (% of SC length). Gamma distribution parameters that best fit the observed frequency distributions of inter-focus distances were calculated. Where indicated, bivalents were further subdivided into groups of similarly sized chromosomes as described in the text and the legend to Table 1.aNumber of interfocus distances analyzed.bShape parameter (��) and standard error (SE). A larger value of �� indicates a more even spacing of MLH1 foci and thus greater cytological interference.cGoodness-of-fit of the experimental data to the gamma distribution (high p value indicates better fit).dCorrected shape parameter. The gamma distribution assumes theoretical limits of infinitely small and infinitely large interfocus distances, but the actual range of inter-focus distances that can be detected is limited by the resolution of light microscopy and by the finite length of each SC. Corrections for these limits were estimated as described in [51].