Cryopreservation of Human Embryos and Oocytes
A procedure to cryopreserve mammalian embryos resulting in the birth of offspring was first described almost forty years ago. This procedure resulting in the birth of a child was reported 26 years ago. Since then, the preservation of human oocytes and embryos by cooling them to low subzero temperatures has become an integral part of Assisted Reproductive Technologies (ART). Hundreds of thousands of children have now been born after having been cryopreserved as oocytes or embryos. These results owe as much to the fundamental understanding of cryobiology as to the application of reproductive medicine. This brief review summarizes the history of embryo cryobiology, and presents a synopsis of basic cryobiology as it applies to present methods to improve the cryopreservation of human oocytes.
Available from: Eleonora Porcu
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ABSTRACT: This review deals with cryopreservation which is one of the most stimulating aspects of the assisted reproduction technology (aRT). The main ad - vantages of this technique include storage for future use without repeating ovarian stimulation and chance of fertility for oncologic patients who are undergoing chemotherapy. The use of cryopreservation by many infertility and ivF centres determined a significant improvement of this technique and a greater interest for long-term effects too, in particular for newborns' health. The present review depicts the studies conducted in this direction. The recent literature shows encouraging results regarding the safety of cryopreservation, although not all techniques have the same support of longi - tudinal studies. Today human sperm cryopreservation is a consolidated and safe procedure. an apparently normal development and growth of the few children born from frozen eggs was also reported by several studies but an international register and follow up is mandatory. Finally, children born after transfer of frozen-thawed embryos seem to be healthy according to the studies performed so far even though further investigations are needed. Cryop -
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ABSTRACT: Our goal was to develop a standardized approach for sperm vitrification of marine fish that can be applied generally in aquatic species. The objectives were to: (i) estimate acute toxicity of cryoprotectants over a range of concentrations; (ii) evaluate the properties of vitrification solutions (VS); (iii) evaluate different thawing solutions and (iv) evaluate sperm quality after thawing by examination of motility and membrane integrity. Sperm were collected from red snapper (Lutjanus campechanus), spotted seatrout (Cynoscion nebulosus) and red drum (Sciaenops ocellatus). A total of 29 combinations of cryoprotectants were evaluated for toxicity and glass formation. Samples were loaded onto 10-μL polystyrene loops and plunged into liquid nitrogen. There was a significant difference (P < 0.05) in post-thaw motility among VS and among species when using the same VS. The sperm in VS of 15% DMSO + 15% ethylene glycol + 10% glycerol + 1% X-1000™ + 1% Z-1000™ had an average post-thaw motility of 58% and membrane integrity of 19% for spotted seatrout, 38% and 9% for red snapper, and 30% and 19% for red drum. Adaptations by marine fish to higher osmotic pressures could explain the survival in the high cryoprotectant concentrations. Vitrification offers an alternative to conventional cryopreservation.
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