Chromosomes are highly elastic and can be stretched.

Direct manipulation of human chromosomes in metaphase spreads using glass needles revealed that the consistency of chromosomes varies depending on their moisture content. Chromosomes are soft and highly elastic under wet conditions and are hard when dry. The elasticity of chromosomes is comparable to rubber threads and can be used for stretching experiments under phase contrast microscopy, after Giemsa staining, and after GTG-banding. The coiling structures of the chromosomes appear to be stretched evenly along the length of the chromosome. Chromosomes fixed for only a short time have a tendency to tear when stretched more than 5 times their length. Under the experimental conditions used, chromosomes were preferentially torn in the centromeric region. Chromosome stretching on GTG-banded human chromosomes leads to a splitting of bands into their subbands. This may be useful for creating new high resolution ideograms possibly showing more than 1700 bands per haploid set.