Chiasma Interference Map (CHIM) of human chromosome 9. The data are based on direct measurements (see Fig 5) in 366 spermatocytes from 10 normal human males. The × axis represents the chromosome and the vertical black line the centromere position. The figure illustrates the frequency of chiasmata along the length of the chromosome arms and the interference distances in each spermatocyte separately. Interference loops, which involve nearly the whole chromosome are black, the near telomere plus interstitial ones are green and blue respectively, dependent on whether the near terminal chiasma is located at 9p or 9q, while those which involve interstitial chiasmata only are red. The barcode diagram shows the chiasma-derived 1 cM genetic map calculated from the centromere towards the telomeres. Note the large pericentromeric gap. The near telomere gaps are artifacts due to any chiasmata within the width of the chromosome being recorded as strictly terminal. Revised from .