Laser-assisted microdissection of the zona pellucida facilitates polar body biopsy

Objective: To investigate whether polar body biopsy can be performed after laser microdissection of the zona pellucida (ZP). Design: Mouse zygotes were allocated randomly to three groups. The zygotes were subjected to laser microdissection of the ZP and polar body biopsy (group 1), laser microdissection alone (group 2), or no treatment (group 3). Setting: University-based IVF program. Patient(s): Animal study. Intervention(s): A hole was drilled in the ZP of mouse zygotes using a 1.48-mu m noncontact diode laser. A microneedle was inserted and the polar body was aspirated. Main Outcome Measure(s): The efficacy of polar body biopsy after laser microdissection of the ZP was evaluated. Result(s): The laser diode beam allowed for precise drilling of a 14- to 18-mu m hole in the ZP. Polar bodies could be aspirated without damaging the zygote and did not disintegrate during the biopsy. Zygotes developed to blastocysts and underwent the same hatching as control zygotes. Lower hatching rates were observed in untreated zygotes. Conclusion(s): Laser microdissection of the ZP with a noncontact laser system facilitates subsequent polar body biopsy. The use of blunt-ended micropipettes greatly reduces the risk of damage to the zygote or the polar body. This procedure makes polar body biopsy more accurate and effective for preimplantation genetic diagnosis. (C) 1998 by American Society for Reproductive Medicine.