ABSTRACT: To evaluate the implantation rate achieved after chemical removal of the zona pellucida from day 5 human in vitro-derived embryos.
Prospective, randomized, controlled study.
A tertiary care infertility clinic.
Two hundred fifty-seven patients undergoing IVF with transfer of morulas or blastocysts on day 5 after oocyte retrieval. All patients had had at least two previous implantation failures.
Chemical removal of zona pellucida by using acidic Tyrode's solution vs. no removal (controls).
Clinical pregnancy rate and implantation rate per transfer.
Embryos without zona pellucida implanted at nearly twice the rate of control embryos (15.7% vs. 27.5%). The pregnancy rate was also significantly higher in the zona pellucida-free group than the control group (31.0% vs. 46.1%). Removal of zona pellucida was most effective in embryos with delayed development, which reached the morula or early cavitating stage on day 5 of in vitro culture (implantation rate, 12.1% vs. 25.7%).
Chemical removal of zona pellucida from day 5 in vitro cultured human embryos is an effective and safe method of significantly improving the implantation rate, especially of embryos with delayed development.
Fertility and Sterility 07/2003; 79(6):1299-303. · 3.56 Impact Factor
Fertility and Sterility 05/2002; 77(4):846-7. · 3.56 Impact Factor
ABSTRACT: To report an ongoing twin pregnancy after transfer of embryos that were vitrified at the 2-pronuclei stage in a new vitrification solution.
A tertiary-care infertility clinic.
A 26-year-old infertile woman in whom two previous IVF implantations failed.
Vitrification of 2-pronuclei embryos, in vitro culture for 48 hours, and transfer into the uterus.
Survival and cleavage after vitrification and achievement of clinical pregnancy.
Six zygotes were vitrified by using a three-step protocol (4% ethylene glycol for 3 minutes, 20% ethylene glycol for 1 minute, and 38% ethylene glycol and 1.2 M trehalose for 0.5 minute). After 2 months of storage in a double-straw system in liquid nitrogen, two zygotes were warmed and cryoprotectants were removed by using a four-step protocol (1 M, 0.5 M, 0.25 M, and 0.125 M of trehalose). Two embryos were transferred after 48 hours of in vitro culture, cleaving to 5 and 6 cells. The resulting twin pregnancy was confirmed by ultrasonography at the sixth week.
Vitrification by using ethylene glycol and trehalose appears to be a safe, promising method for cryopreservation of human zygotes. Storage of vitrified zygotes in a double-straw system does not compromise their subsequent potential for survival and development.
Fertility and Sterility 03/2002; 77(2):412-4. · 3.56 Impact Factor
ABSTRACT: Reduced oxygen concentration has been shown to improve only the latter stages of preimplantation development of human embryos in vitro (days 4–6 of culture), resulting in higher incidence of blastocyst formation and higher number of blastomeres. Our study was focused on the effect of different O2 concentrations on the cleavage kinetics and fragmentation rate during the first 2 or 3 days of in vitro culture. Embryos from 400 patients were cultured at 20% or 5% of O2. Morphologic evaluation of embryos was performed at 39–42 h after insemination or ICSI for day 2 transfer and at 63–66 h for day 3 transfer, respectively. Data were analysed by χ2 test. On day 2, the mean cell number of all embryos cultured at 5% O2 was significantly higher (p<0.05) than of those embryos cultured at 20% O2 (3.62 vs. 2.87, respectively). The similar results were observed on day 3 (6.31 vs. 5.86, respectively, p<0.05). Fragmentation rate was significantly lower in the embryos cultured at 5% O2 as compared with those embryos cultured at 20% O2 (67.7% vs. 42.3% of embryos with less than 10% fragmentation, p<0.01). In conclusion, we have observed significantly faster kinetics of cleavage and lower fragmentation rate in the group of embryos cultured at lower O2concentration (5%) as compared to embryos cultured at 20% of O2 during the first 3 days of in vitro culture.
International Congress Series 1271:147-150.