Use of a laser to evaluate zona pellucida hardness at different stages of mouse embryonic development in vitro and in vivo

Possible applications of a non-contact 1.48 μm wavelength diode laser in assisted reproduction technologies

Recently, one laser system has been introduced in IVF fulfilling all safety requirements, while achieving a high standard of reproducibility in terms of ablation diameter. This 1.48 microm wavelength indium-gallium-arsenic-phosphorus (InGaAsP) semiconductor laser offers a variety of laser applications to the embryologist. On the one hand, zona pellucida of oocytes or embryos can be manipulated in order to facilitate ICSI or biopsy and assist hatching, and on the other, spermatozoa may be paralysed or immobilized prior to usage. To conclude, the 1.48 microm diode laser provides a promising tool for the microdissection of subcellular targets. The diode laser stands out due to the rapidity, the simplicity and the safety of the procedure which is supported by healthy offspring after laser application.

A European multicentre prospective randomized study to assess the use of assisted hatching with a diode laser and the benefit of an immunosuppressive/antibiotic treatment in different patient populations

BACKGROUND

Assisted hatching (AH) techniques, designed for facilitating the embryo escape out of the zona pellucida (ZP) have been used in IVF centres since 1992. The initial indications for AH were patient's age, ZP thickness, high basal FSH and repeated IVF failures. Several retrospective and prospective studies assessing AH in these indications have given disparate results. Our aims were to evaluate the benefits of AH and immunosuppressive/antibiotic treatment (IA) in patients with either a poor prognosis of success, previous implantation failures or transfers of cryopreserved embryos.

METHODS

Four IVF centres allocated 426 patients, randomized for AH and IA, into four groups of AH indications between 1997 and 1999. AH was performed with a diode laser. ZP thickness, opening size and embryo score were recorded. Outcome measures were implantation and delivery rates.

RESULTS

Patients coming for a first or third transfer of cryopreserved embryos and poor prognosis patients admitted for a first trial did not benefit from AH. Even patients with repeated implantation failures of fresh embryos did not gain significantly from AH.

CONCLUSIONS

Among AH indications, absence of implantation after several transfers of good quality embryos remains the strongest patient selection criterion. Prescription of an immunosuppressive/antibiotic treatment is essential.

Effects of different laser-drilled openings in the zona pellucida on hatching of in vitro-produced cattle blastocysts

OBJECTIVE

To examine whether the size of artificial openings in the zona pellucida effects the hatching process in in vitro-produced cattle embryos.

DESIGN

We evaluated the course of hatching of cattle blastocysts with and without laser-drilled zona pellucida openings of different sizes.

SETTING

University-based cattle reproductive biotechnology laboratory.

INTERVENTION(S)

Cattle blastocysts were produced in vitro. Laser treatment was performed 7 days after fertilization. In group I, a small opening of 7-15 microm in width and 40 microm in length was created. In group II, an opening of at least 40 by 40 microm was created. Group III blastocysts received no laser treatment.

MAIN OUTCOME MEASURE(S)

Hatching course, zona pellucida thickness, diameter.

RESULT(S)

By day 9, the rate of hatched blastocysts was 27.1%, 63,0%, and 42,9% in groups I, II, and III, respectively. The remainder in group I were entrapped during hatching in a typical figure eight shape. The hatching rate in group II was significantly different from the other groups. All laser-treated blastocysts (groups I and II) showed no change of zona pellucida diameter until day 9.

CONCLUSION(S)

These results suggest that the size of the artificial openings in the zona pellucida has an influence on the hatching process.