Microdissection of mouse and human zona pellucida using a 1.48-microns diode laser beam: efficacy and safety of the procedure.

OBJECTIVE

To investigate the efficacy and safety of a small and affordable 1.48-microns continuous wave diode laser for zona pellucida (ZP) microdissection.

DESIGN

Mouse and human oocytes and zygotes were submitted to ZP drilling. The hole characteristics and possible laser-induced structural alterations of the neighboring cytoplasm were investigated with scanning and transmission electron microscopy. The safety of the procedure was checked on control and drilled zygotes by determining their ability to develop in vitro and in vivo.

SETTING

Collaborative study between three Swiss academic centers.

INTERVENTIONS

The collimated diode laser beam was delivered through a 45x objective of an inverted microscope and focused through the culture dish and culture medium in 1- to 3-microns spots.

MAIN OUTCOME MEASURE

Safety assessment of the laser drilling procedure.

RESULTS

The 1.48-microns radiation achieves a rapid, precise, and easily controlled lysis of the ZP without any micromanipulative handling of the eggs. Different shapes of holes can be produced by varying the laser beam intersection site on the ZP, laser power, and irradiation time. The energy needed to drill holes of a given diameter is greater for zygotes than for oocytes. Safety of the drilling procedure is confirmed by the lack of damage at the ultrastructural and biologic levels.

CONCLUSIONS

The low-cost 1.48-microns diode laser allows an easy, objective-driven, nontouch microdissection of the ZP. The procedure is safe, as drilled embryos give rise to normal and fertile offspring.