The polar body (PB) technique makes use of the 23 chromosomes contained in the first polar body, a part of the egg that is extruded at ovulation. Normally the first polar body disintegrates. However, it can be salvaged by polar body biopsy prior to this so that the chromosomes within can be analyzed. PB has three distinct advantages over conventional Fluorescent in-situ Hybridization (FISH) analysis. First, the polar body biopsy is performed on the day that the oocyte is retrieved (day 0) rather than day 3 so results are available earlier. Secondly, this methodology does not remove cells from the growing embryo. The polar body biopsy removes genetic material that would otherwise degrade. Finally, microarray analysis evaluates all 23 chromosomes while only 9-10 chromosomes can be studied with FISH analysis.