Potassium Chloride (KCl), 0.075 Molar

A major step in harvesting cells for chromosome karyotyping is treatment with a hypotonic saline solution to increase cell volume. Hypotonic solutions work by creating a concentration gradient across the cytoplasmic membrane and water then rushes in by active transport.

Potassium Chloride (KCl, or potassium salt) is a hypotonic solution prepared in water for use in the preparation of blood lymphocyte chromosomes, the hypotonic treatment allows the cells to take in water and swell. At this step, the cells resemble balloons ready to burst and release their contents, which is the goal of this procedure.