BACKGROUND Cleavage stage embryos as well as postimplantation embryos have been studied extensively over the years. However, our knowledge with respect to the chromosomal constitution of human embryos at the blastocyst stage is still rudimentary. METHODS In the present paper, a large series of human blastocysts was examined by means of fluorescent in situ hybridization (FISH). RESULTS It wa...

The moral status of the human embryo has gained much attention in debates over the acceptability, or otherwise, of human embryonic stem cell research. Far less attention has been paid to the suppliers of those embryos: people who have undergone IVF treatment to produce embryos to assist them to have a baby. It is sociologically and ethically important to understand their views and experiences o...

Knowledge on determination and differentiation in the mammalian embryo has not kept pace with discoveries in other phyla. Current concepts overlook well-established pathways leading to polarity in oocytes and embryos of other phyla, modern principles of totipotency in plants and animals, and axis formation in lower vertebrates. Various models derived from invertebrates and frogs could be releva...

The Ped gene influences the rate of cleavage division of preimplantation mouse embryos and subsequent embryonic survival. The mouse Ped gene product is a major histocompatibility complex (MHC) class Ib protein called Qa-2. Studies from many human in-vitro fertilization (IVF) clinics suggest that the mouse Ped gene has a human homologue because embryos fertilized at the same time have different ...

This study investigated the relationship between human preimplantation embryo metabolism and aneuploidy rates during development in vitro. One hundred and eighty-eight fresh and cryopreserved embryos from 59 patients (33.9 +/- 0.6 years) were cultured for 2-5 days. The turnover of 18 amino acids was measured in spent media by high-performance liquid chromatography. Embryos were either fixed for...