Background: The maternal age effect for trisomy is well known. However what is less established is whether certain women are more (or less) prone to segregation errors, independent of age. Trisomy arises primarily through maternal meiosis I chromosome segregation errors however the precise mechanism by which these errors occur is unclear. Current dogma attributes the origin of trisomy to malseg...

The establishment of DNA methylation patterns in oocytes is a highly dynamic process marking gene-regulatory events during fertilization, embryonic development, and adulthood. However, after epigenetic reprogramming in primordial germ cells, how and when DNA methylation is re-established in developing human oocytes remains to be characterized. Here, using single-cell whole-genome bisulfite sequ...

Induced pluripotent stem cells (iPSCs) hold much promise in the quest for personalised cell therapies. However, the persistence of founder cell mitochondrial DNA (mtDNA) mutations limits the potential of iPSCs in the development of treatments for mtDNA disease. This problem may be overcome by using oocytes containing healthy mtDNA, to induce somatic cell nuclear reprogramming. However, the exte...

Since the first successful pregnancy from a frozen human oocyte was reported, remarkable technological progress has been made in the area of cryopreservation of human oocytes. We report a successful delivery of two healthy babies after transfer of vitrified-warmed embryos derived from intracytoplasmic sperm injection (ICSI) with vitrified-warmed oocytes and frozen-thawed sperm. A female patient...

We describe the cloning of HOXD1 in human unfertilised oocytes and detailed expression analyses during mouse oogenesis and embryogenesis. The cDNA of 1991bp has an open reading frame of 987bp encoding a protein of 329 amino acids. A comparison of the amino acid sequence with the mouse homologue revealed an overall homology of 85.5% with 99% identity within the homeodomain. Expression was detect...

STUDY QUESTION Can complete oocyte development be achieved from human ovarian tissue containing primordial/unilaminar follicles and grown in vitro in a multi-step culture to meiotic maturation demonstrated by the formation of polar bodies and a Metaphase II spindle? SUMMARY ANSWER Development of human oocytes from primordial/unilaminar stages to resumption of meiosis (Metaphase II) and emissi...

The acrosome reaction by spermatozoa is an indispensable prerequisite for fertilization, and zonae pellucidae of human oocytes induce this reaction in the human spermatozoa attached to them. Human spermatozoa can attach to the zona pellucida of hamster oocytes when the oocytes have been treated with trypsin. We examined whether or not trypsin-treated hamster zona pellucida induces the acrosome ...

= Abstract = Follicular fluids and their matched oocytes were obtained from 16 follicles of 7 women who conceived after in vitro fertilization(IVF), and 49 follicles of 17 women who failed to conceive after the procedure. Follicular development was induced with a combination of follicle-stimulating hormone and human menopausal gonadotropin. There was no significant difference in follicular cycl...

The first meiotic division in human oocytes is highly error-prone and contributes to the uniquely high incidence of aneuploidy observed in human pregnancies. A successful meiosis I (MI) division entails separation of homologous chromosome pairs and co-segregation of sister chromatids. For this to happen, sister kinetochores must form attachments to spindle kinetochore-fibres emanating from the ...

BACKGROUND This study was conducted to investigate the fertilization and embryo development of human oocytes injected at different time intervals after extrusion of the first polar body (PB) following in vitro maturation (IVM) in IVM cycles. Also, we evaluated whether spindle imaging could serve as a tool to determine the optimal ICSI time. METHODS Oocytes were collected from 43 women with po...