Here’s a brief overview of the novelties in embryology presented in during this annual meeting of ESHRE.
Recent findings on ‘Oliana strings’, named after the embryologist who characterised them, were discussed on Monday. Such structures, observed in 77% of embryos, are in fact an extension of the corona cell interacting with the oolemma. They are associated with embryo fragmentation but have no effect on ploidy or implantation rate.
Next, the highly controversial question of assisted hatching was addressed by Kenji Ezoe, who provided new insights into the molecular mechanisms (increased expression of integrin α5β1 mRNA in fully hatched embryos) involved in the attachment of a fully hatched embryo after warming. He concluded that blastocyst adhesion rate was 20% and 70% higher in complete ZP removal group as compared to the intact and partially hatched embryos.
Culture media are still the subject of great attention. Ellen Casser described the creation monozygotic twin mouse embryos and their culture in different culture media to test their impact on the developing embryos and subsequent pups. It also seems that the composition and physico-chemical properties of culture media vary throughout storage; we were warned that commercial culture media may be contaminated with company staff cell-free DNA! The question of any potential impact on embryo remains unanswered…
Non-invasive approaches to select the most viable embryo for a singleton pregnancy are still being developed: Dr Sakkas proposed non-invasive fluorescence lifetime imaging microscopy (FLIM) as a system for comprehensive embryo metabolism measurement. It was also shown that culture medium lipid fingerprint and the microRNA (MiR-142-3p) are potential markers for implantation success. Use of time-lapse systems was also behind the identification of novel phenomena associated with fertilisation known as cytoplasmic waves, which may predict embryo implantation.
Debbie Montjean, SIG Embryology Junior Deputy