Zona drilling and sperm insertion with combined laser microbeam and optical tweezers.

A combined UV-laser microbeam and optical-tweezers trap was used to perform laser zona drilling and subzonal insemination in cattle. Using a precisely focused UV-laser microbeam, a small channel of about 10 microns in diameter was drilled into the zona pellucida. With a three-dimensional optical-tweezers trap, a single sperm was caught and transported through the laser-drilled hole directly into the perivitelline space. Furthermore, the sperm was brought into close contact with the oolemma to facilitate sperm-oocyte fusion. Using the laser-microscope system, noncontact, entirely sterile, and highly selective micromanipulation of gametes can be achieved with no need for mechanical microtools. Laser micromanipulation seems to be less detrimental to the gametes and is comparatively is easy to perform. Thus, the combined UV-laser microbeam and optical tweezers trap may be a helpful tool for IVF procedures.