The YAG laser used in micromanipulation to transect the zona pellucida of hamster oocytes

Randomized controlled study of human zona pellucida dissection using the zona infrared laser optical system: evaluation of blastomere damage, embryo development, and subsequent hatching

OBJECTIVE

To assess the effect of laser hatching on human embryo damage and subsequent development using the Zona Infrared Laser Optical System (ZILOS).

DESIGN

Randomized controlled study.

SETTING

Tertiary care fertility clinic.

PATIENT(S)

One hundred fourteen donated and discarded frozen human embryos.

INTERVENTION(S)

Embryos were thawed, cultured with cleavage and morphology evaluated periodically, and randomized into control, partial hatching, or complete hatching groups. The laser hatching procedure was performed by ZILOS. Zona thickness and embryo diameter were recorded. Complete hatching involved the production of a full-thickness defect in the zona and partial hatching, a defect in the outer half of the zona. No laser treatment was administered to the control group.

MAIN OUTCOME MEASURE(S)

Blastocyst development and completion of hatching process.

RESULT(S)

No significant difference was noted between the three study groups for their baseline characteristics. There was no significant difference in blastocyst development among the three groups. However, the complete hatching group showed a significant increase in hatching compared to the control group.

CONCLUSION(S)

Complete laser hatching of human embryos using the ZILOS does not have an adverse effect on subsequent development and increases the rate of completion of hatching.

Laser scissors and tweezers

In summary, we described the use of laser scissors and tweezers from three perspectives: (a) the historical background from which these two techniques evolved, (b) an understanding and lack of understanding of the mechanisms of interaction with the biological systems, and (c) the applications of the scissors and tweezers alone and in combination. As the technology improves and we gain a better understanding of how these two tools operate they will become even more useful in probing cell structure and function, as well as practically manipulating cells in genetics, oncology, and developmental biology.