Chromosome Hypotonic Treatment

A hypotonic solution, such as 0.075M KCl, has a lower salt concentration than the cytoplasm of the cells. According to the osmotic laws extracellular water will therefore penetrate into the cells, whereby they swell. This facilitates the spreading of the chromosomes when the fixed cell syspension is dropped onto glass slides. Insufficient hypotonic treatment result in metaphase spreads with tightly packed and overlapping chromosomes, where it is hard to count the chromosomes and analyse the individual chromosomes for structural abnormalities.