The chiasma pattern in a human male reciprocal 1;22 translocation carrier. Pictures of translocation quadrivalents at the Diakinesis/Metaphase I stage in spermatocytes from a carrier of a reciprocal 1; 22 translocation with the corresponding drawings showing the interpretation of the chiasma patterns (top). Note the high frequency and different distribution of chiasmata within the interstitial segment between the centromere and the breakpoint. The translocation carrier shows a raised chiasma frequency and altered chiasma distribution in chromosome 1, particularly in the region adjacent to the breakpoint (grey staples) in comparison to six controls with normal karyotypes (bottom). Reproduced from .