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Background: Recent studies have shown that zygote morphology could be used for the assessment of human embryo quality. Pronuclear (PN) morphology is based on certain distinct features seen in zygotes 16-18 h after fertilization. In the present study PN stage morphology was assessed and combined with a single embryo transfer in order to investigate whether currently used zygote classifications are able to predict embryo quality and implantation rates.Methods and Results: Zygotes were analysed according to two different classification systems. In the first, a total of 764 zygotes was analysed according to the degree of polarization of nucleolar precursor bodies (NPB). Zygotes with unpolarized PN (i.e. scattered localization of NPB) showed significantly slower (P < 0.005) cleavage rates (38.9%) than zygotes having at least one pronucleus polarized (57.3% and 54%). However, there was no difference in the pregnancy rate in 105 single embryo transfers between the groups. The appearance of a cytoplasmic halo was related to embryo morphology. Embryos derived from halo-positive zygotes had significantly better (P < 0.05) morphology (60.9%) compared to halo-negative derived embryos (52.2%), but in terms of pregnancy rates no difference was found. A total of 1520 zygotes was analysed according to a second classification system, which was based on the number and distribution of NPB. In the comparative analysis, none of the six different classes produced superior quality embryos or higher pregnancy rates in 144 single embryo transfers.Conclusions: Our results indicate that there are no significant differences in embryo quality or implantation/pregnancy rates between proposed zygote classes. [ABSTRACT FROM AUTHOR]

In this prospective study we investigated whether the maturation and fertilization of immature oocytes can be improved by administration of recombinant follicle stimulating hormone (rFSH) starting in the late luteal phase in two groups of women: group 1 (n = 6) women with regular menstrual cycles; and group 2 (n = 6) women with irregular cycles and polycystic ovaries (PCO) on ultrasound examination. Low-dose (37.5 IU) rFSH was commenced 11 days after LH surge during a spontaneous menstrual cycle and on the ninth day of progesterone administration in an irregular cycle. Recombinant FSH was continued until the leading follicle was approximately 10 mm in diameter. The oocytes were retrieved after withdrawing rFSH for 2-5 days. In total, 136 oocytes were recovered (group 1, 67 oocytes; group 2, 69 oocytes). Nine of the oocytes from PCO women were atretic at retrieval. Oocytes complete with cumulus cells were cultured for 44 h in complex tissue culture medium supplemented with gonadotrophins and fetal calf serum. After maturation, the cumulus cells were removed and metaphase II oocytes were injected with spermatozoa. Respectively, the oocyte maturation and fertilization rates were 64 and 72% in group 1, and 78 and 57% in group 2 (not significant). After fertilization, the zygotes (group 1, n = 22; group 2, n = 11) and cleavage stage embryos (group 1, n = 9; group 2, n = 15) were frozen in propanediol. All women except one (11/12) had approximately five zygotes or cleaved embryos frozen. The viability of in-vitro matured frozen-thawed embryos was generally poorer than that (81%) seen after conventional intracytoplasmic sperm injection, with 61% survival in group 1 and 23% in group 2. Fifteen embryo transfers resulted in one miscarriage at 6 weeks gestation. The late luteal start of low-dose rFSH yielded a good number of immature oocytes in women with both regular and irregular cycles. Two out of three of these oocytes matured and fertilized. However, cryosurvival of the zygotes and cleaved embryos was unsatisfactory and thus cryopreservation of in-vitro matured embryos may not be an optimal procedure. [ABSTRACT FROM AUTHOR]

A randomized comparison of two recombinant human follicle-stimulating hormone (recFSH) preparations (Gonal-F and Puregon) in ovarian stimulation for in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) was carried out at the Infertility Clinic of the Family Federation of Finland. A total of 348 women (aged 22-43 years) suffering from infertility due to miscellaneous causes was recruited. Of these, 344 underwent stimulation using equal starting doses (150 IU/day: Gonal-F n = 164, Puregon n = 158 or 300 IU/day: Gonal-F n = 8, Puregon n = 14) after down-regulation with intranasal buserelin from the mid-luteal phase. Similar clinical pregnancy rates were achieved with both preparations; 33.5% per cycle and 37.4% per embryo transfer (24.5% one-embryo and 75.5% two-embryo transfers, n = 147) with Gonal-F (150 IU/day) and 32.9% per cycle and 36.4% per embryo transfer (30.1% one-embryo and 69.9% two-embryo transfers, n = 145) with Puregon (150 IU/day). The ongoing cumulative pregnancy rates after frozen-thawed embryo transfer were 35.4% with Gonal-F and 37.7% with Puregon. Six cycles were cancelled because of a low response (three in each group). Similar numbers of oocytes were obtained in both groups; 13.0 with 150 IU/day and 6.1 with 300 IU/day Gonal-F, and 12.4 with 150 IU/day and 7.1 with 300 IU/day Puregon. The fertilization and cleavage rates and the incidence of moderate or severe ovarian hyperstimulation syndrome (Gonal-F, 2.0% and Puregon, 0.7%) were also similar. Gonal-F and Puregon were equally and highly effective in stimulation for IVF and ICSI. [ABSTRACT FROM AUTHOR]