Inm-1: Blastocyst Culture: Advantages and Disadvantages

Both cleavage-stage and blastocyst-stage embryo transfer policieshave advantages and drawbacks.Potential advantages of blastocyst culture and transfer in human IVF include: i. synchronization of the embryo with the female tract leading to increasedimplantation rates; thereby, reducing the need for multipleembryo transfers, ii. assessment of viability of an embryobefore transfer. This can be achieved by both the identification of those embryos with little developmentalpotential, as manifest by slow development or degenerationin culture, and by the introduction of non-invasive tests of developmental potential to select the most viable embryosfrom within a cohort for transfer. Furthermore, culture of the human embryo beyond the 4-8-cell stage, the time at which the genome is activated, will facilitate the quantification of true embryonic markers as opposed to those inherited from the oocyte, i.e. after the 8-cell stage oneis assessing embryo physiology, while prior to this the physiology of the cleavage stage embryo reflects that of the oocyte, iii. an increase in the time available between cleavage stage embryo biopsy and embryo transfer. This is of particular importance where the biopsied material has to be sent to a separate locale for analysis, and iv. facilitation of the introduction of trophectoderm biopsy for the screening of genetic diseases. Trophectoderm biopsy represents the earliest form of genetic diagnosis of non-embryonicmaterial.