Preimplantation or pre-attachment development encompasses the "free"-living period of mammalian embryogenesis, which directs development of the zygote through to the blastocyst stage. Blastocyst formation is essential for implantation, establishment of pregnancy and is a principal determinant of embryo quality prior to embryo transfer. Cavitation (blastocyst formation) is driven by the expressi...

Uterine contractility decreases at the time of blastocyst transfer Dear Sir, Fanchin and co-workers (Fanchin et al., 2001) should be congratulated for publishing a very well written paper on the role of uterine contractions in assisted reproduction. They provide convincing evidence that uterine contractility at the time of theoretical blastocyst transfer (7 days after HCG injections or 5 days a...

Sir, We readwith interest the recent article (Dar et al., 2013) suggesting that singletons born after extended culturemay have a higher risk of preterm delivery than those born after Day 3 transfer. While the importance of optimizing embryo culture and improving obstetrical outcomes after in vitro fertilization should not be underestimated, we believe this study suffers from a serious methodolo...

2- to 4-cell and morula- to blastocyst-stage mouse embryos were cultured for 1 h in tritiated leucine at two specific activities and their subsequent development followed in vitro and in vivo (after transfer to recipients), respectively. 2- to 4-cell embryos that incorporated an average of 42 d.p.m. per embryo were impaired in their ability to develop to the morula and blastocyst stage. Recipie...

BACKGROUND There are conflicting results on whether the rate of blastocyst development before freezing influences the outcome of frozen-thawed blastocyst transfers. METHODS We conducted a systematic review and meta-analysis of controlled studies to compare pregnancy outcomes following transfer of thawed blastocysts that were frozen either on Day 5 or Day 6 following fertilization in vitro. Se...

We compared two methods of zona pellucida drilling. 213 embryos were biopsied with acid Tyrode. Each biopsy took 3 minutes and the entire procedure ~29 minutes. 5% of blastomeres lysed, 49% of embryos became blastocyst and 36% of patients became pregnant. 229 embryos were biopsied with laser. Each biopsy took 30 seconds and the entire procedure ~7 minutes. 2.5% of blastomeres lysed, 50.6% of em...

This research was designed to study in vitro development of bovine nuclear transferred embryos using enucleated young in vitro matured oocytes 24 h of age as recipient cytoplasts activated prior to nuclear transfer. The oocytes were enucleated and then activated with electric pulse at 24 h of age followed by incubation with cycloheximide for 6-7 h before nuclear transfer and membrane fusion wit...