3 research outputs found
Controlled stress improves oocyte performance : cell preconditioning in assisted reproduction
A recently emerged concept utilizing a controlled environmental impact as a treatment for cells and tissues aims to improve neither the in vitro conditions nor the procedures, but the cell itself. Hydrostatic pressure stress emerged as the most controllable and most effective stressor, proving the principle that controlled stress improves cell performance in in vitro procedures, whereas further studies using different stressors (osmotic, oxidative or mechanic stresses) supported the principle. The present summary reviews studies of various stress treatments to treat oocytes of three species (murine, porcine, human) before vitrification, in vitro maturation, enucleation and somatic cell nuclear transfer. Eventually, cleavage and blastocyst rates and – in cases when hydrostatic pressure was used – blastocyst cell number and birth rates as well were significantly improved compared to untreated controls
Pregnancy achieved by transfer of a single blastocyst selected by time-lapse monitoring
Appropriate selection of a single blastocyst for transfer decreases the risk of multiple gestations. By using a compact time-lapse microscope system placed inside a regular incubator, combined with a microwell embryo culture dish, the development of all the embryos from a patient was continuously monitored by obtaining images at 10 min intervals. The embryos were not moved during the time-lapse observation. The system was switched off completely between image acquisitions in order to avoid exposure to electromagnetic radiation. The analysis of time-lapse records was used to choose a single blastocyst for transfer, which resulted in a singleton pregnancy and birth of a healthy boy on term
Prediction of in-vitro developmental competence of early cleavage-stage mouse embryos with compact time-lapse equipment
Single blastocyst transfer is regarded as an efficient way to achieve high pregnancy rates and to avoid multiple pregnancies. Risk of cancellation of transfer due to a lack of available embryos may be reduced by early prediction of blastocyst development. Time-lapse investigation of mouse embryos shows that the time of the first and second cleavage (to the 2- and 3-cell stages, respectively) has a strong predictive value for further development in vitro, while cleavage from the 3-cell to the 4-cell stage has no predictive value. In humans, embryo fragmentation during preimplantation development has been associated with lower pregnancyrates and a higher incidence of developmental abnormalities. Analysis of time-lapse records shows that most fragmentation is reversible in the mouse and is resorbed in an average of 9 h. Daily or bi-daily microscopic checks of embryo development, applied routinely in human IVF laboratories, would fail to detect 36 or 72% of these fragmentations, respectively. Fragmentation occurring in a defined time frame has a strong predictive value for in-vitro embryo development. The practical compact system used in the present trial, based on the ‘one camera per patient’ principle, has eliminated the usual disadvantages of time-lapse investigations and is applicable for the routine follow-up of in-vitro embryo development