Plasticity of the human preimplantation embryo: developmental dogmas, variations on themes and self-correction

AbstractBACKGROUNDIVF for the treatment of infertility offers unique opportunities to observe human preimplantation development. Progress in time-lapse technology (TLT) and preimplantation genetic testing (PGT) has greatly expanded our knowledge of developmental patterns leading to a healthy pregnancy or developmental failure. These technologies have also revealed unsuspected plastic properties of the preimplantation embryo, at macromolecular, cellular and multicellular levels.OBJECTIVE AND RATIONALEThis review focuses on the emerging concept of plasticity of the human embryo as revealed by recent evidence derived from TLT and PGT, calling for an updated and more precise redefinition of the boundaries between normal and abnormal development.SEARCH METHODSPubMed was used to search the MEDLINE database for peer-reviewed English-language original articles and reviews concerning human preimplantation development. Cross-searches were performed by adopting ‘fertilisation‘, ‘pronucleus’, ‘cleavage’, ‘multinucleation’, ‘compaction’, ‘embryo’, ‘preimplantation genetic testing’, ‘aneuploidy’, mosaicism’, ‘micromanipulation’, ‘time-lapse microscopy’ and ‘IVF/assisted reproduction’ as main terms. The most releva nt publications, i.e. those concerning major phenomena occurring during normal and abnormal development—with a focus on the human species—were assessed and discussed critically.OUTCOMESAdvances in TLT and PGT have revealed an asto...
Source: Human Reproduction Update - Category: OBGYN Source Type: research