Pre-Hypotonic Solution is supposed to be used before the hypotonic stage of a blood or bone marrow harvest. The solution makes the hypotonic step more practical by avoiding the tendency of chromosomes to clump or to under-spread. The clumping of metaphases throughout the harvesting procedure might typically lead to the loss of functional metaphases or of entire cultures.
Procedures like FISH that demand good well unfolded metaphases are often hampered by this downside. The pre-hypotonic solution was designed to handle this clumping problem. Best metaphase swelling will thereby later be achieved by the hypotonic solution. Pre-Hypotonic resolution has been found to be significantly helpful for template CGH metaphases. CGH hybridisations are improved by Pre-Hypotonic solution.