Non-random centromere division: analysis of G-banded human chromosomes.

The distribution by individual chromosomes of early centromere divisions was investigated in two series of G-banded lymphocyte culture preparations. 1. Photographs of mitoses of routinely karyotyped 201 healthy persons were retrospectively analysed. 2. In a prospective study, 48 h and 72 h cultures of 12 girl infants were examined. The results were very similar in both series. They confirm a non-randomness of centromere separation which seems to be independent of sex and technical factors. The earliest dividing chromosomes were Nos 18, 2, 5, 12 and X, in that order, whereas the acrocentrics were the last to separate. The investigation of asynchronous division may be interesting from the point of view of mechanism of non-disjunction, and of testing mutagenicity.