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26 results

Page 1 of 2

  • Chapter 36 - Clinical potential of in vitro maturation
  • from Section 8 - In vitro follicle growth and maturation
  • Edited by Jacques Donnez, Université Catholique de Louvain, Belgium, S. Samuel Kim, University of Kansas
  • Book: Principles and Practice of Fertility Preservation
  • Published online: 04 February 2011
  • Print publication: 03 February 2011, pp 431-439
  • View abstract

    Summary

    Ovarian cryopreservation presents a valid alternative to egg freezing in some circumstances. The possibility to store oocytes for a later use is also an important consideration for women who choose to postpone motherhood for personal or professional reasons. Any newly developed protocol should consider the biochemical and physical properties of the oocyte. In addition to surviving the cryopreservation/warming process, the oocyte needs to maintain competence to fertilize and develop in vitro to the appropriate embryonic stage without any structural alterations. Slow cooling protocol is characterized by a slow decreasing temperature rate. Several mathematical models define an optimal curve applicable to oocytes since the freezing rate is vital to achieve sufficient and progressive dehydration, and thereby minimize the potential of intracellular ice formation. During fresh cycles only a few oocytes can be inseminated; therefore, cryopreservation is the only option to avoid wastage of surplus eggs and consequent repeated ovarian stimulation.
  • Section 5 - Cryopreservation of ovarian tissue
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 189-247
  • View abstract

    Summary

    Cryopreservation of human embryos is an important tool for in vitro fertilization (IVF) practice. Human embryos can be cryopreserved efficiently from the pronuclear to blastocyst stage. For day 2 or day 3 embryos, it is better practically to culture the thawed embryos further for a period of time before transfer in order to confirm that these embryos resume development. The selection method for post-thawed embryos for transfer directly affects the clinical outcome in terms of pregnancy and live birth rates. Two basic techniques have been employed for the cryopreservation of human embryos: slow freezing and vitrification. Slow freezing was used first and is still the most common method for cryopreservation of human embryos. Vitrification is a relatively new technique and has been introduced to cryopreserve human embryos in recent years. Many studies have reported improved success rates in terms of clinical pregnancy and live birth rates with the vitrification technique.
  • 5 - Cryopreservation of sperm:
  • from Cryopreservation of sperm and testicular tissue
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 39-45
  • View extract

    Summary

    Sperm cryopreservation is a widely used and established method in humans, animals, fish, and insects. In humans, sperm cryopreservation is a widely used technique in assisted reproductive technologies (ART) and fertility preservation in patients with cancer. Sperm cryopreservation describes a complex multistep process for preserving male gametes. The process involves collecting a sperm sample, then gradually cooling the sample in the presence of a cryoprotective agent, followed by storage of the sample for future use. Cryoprotectants such as glycerol revolutionized cryopreservation techniques and paved the way for storing sperm samples for up to several years. As new cryoprotectants were discovered, the main issue was the degree of protection that they could provide for a sperm from damage caused by rapid freezing. Future studies are expected to concentrate on advancing technology to achieve the goal of damage-free sperm after cryopreservation.
  • Section 4 - Cryopreservation of oocytes
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 114-188
  • View extract

    Summary

    An effective oocyte cryopreservation program benefits infertile couples with moral or religious objections about cryopreservation of embryos. When considering all pregnancies and live births obtained from cryopreserved oocytes using the classic slow-freezing method, the survival rates averaged approximately 50%. The percentage of live births per thawed egg ranges from 1 to 10% using the classic slow-freezing protocols. Recently, improved survival and pregnancy rates have been reported using modified slow-freezing procedures, particularly increased sucrose concentration in the suspending solution, and the use of sodium-free freezing solutions. Several attempts have been made with immature human oocytes. Although survival rates seemed to be improved by the slow-freezing method, poor in vitro maturation (IVM) and fertilization are major problems associated with immature egg freezing. Rapid cooling (vitrification) of human oocytes has resulted in relatively higher survival rates. This study suggested that better results can be achieved by vitrifying mature oocytes rather than immature oocytes.
  • Cryopreservation of sperm and testicular tissue
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 39-66
  • View extract

    Summary

    Sperm cryopreservation is a widely used and established method in humans, animals, fish, and insects. In humans, sperm cryopreservation is a widely used technique in assisted reproductive technologies (ART) and fertility preservation in patients with cancer. Sperm cryopreservation describes a complex multistep process for preserving male gametes. The process involves collecting a sperm sample, then gradually cooling the sample in the presence of a cryoprotective agent, followed by storage of the sample for future use. Cryoprotectants such as glycerol revolutionized cryopreservation techniques and paved the way for storing sperm samples for up to several years. As new cryoprotectants were discovered, the main issue was the degree of protection that they could provide for a sperm from damage caused by rapid freezing. Future studies are expected to concentrate on advancing technology to achieve the goal of damage-free sperm after cryopreservation.
  • 20 - Obstetric and perinatal outcomes in pregnancies conceived following oocyte cryopreservation
  • from Section 4 - Cryopreservation of oocytes
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 178-188
  • View abstract

    Summary

    Supernumerary embryos may be cryopreserved as early as day 1 (pronuclear stage) and up to day 6 or day 7. This chapter focuses on the crypreservation of pronuclear stage embryos on day 1. Two main methods are used for the cryopreservation of human oocytes and embryos: slow freezing and vitrification. Although controlled slow freezing remains the main method of cryopreservation in most in vitro fertilization (IVF) programs, the vitrification technique has entered the mainstream of human assisted reproductive technology (ART) more and more. Successful pregnancies and live births have been achieved by vitrification of human oocytes and embryos using different carrier systems. The total concentration of cryoprotectant ranges from 5 to 8 mol/l in vitrification protocols currently used in the cryopreservation of human oocyte and embryos. Relatively limited data are available regarding the application of vitrification in the cryopreservation of pronuclear stage human embryos.
  • 17 - Vitrification of human oocytes using the McGill Cryoleaf protocol
  • from Section 4 - Cryopreservation of oocytes
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 144-156
  • View abstract

    Summary

    Advances in assisted reproductive technology (ART) have created opportunities for preservation of the reproductive potential of young males with cancer. Semen cryopreservation is possible in most adolescents with cancer regardless of age or diagnosis. Awareness by physicians is even more essential when dealing with younger populations. Theoretically, testicular tissue from prepubertal boys facing gonadotoxic treatment could be banked for many years for spermatogonial stem cell transplantation. Male germline stem cells are the only cells in postnatal mammals that undergo self-renewal and transmit genes to subsequent generations, since all female germline stem cells cease their proliferation before birth. Future possible methods of restoring fertility might include the derivation of mature sperm cells from human embryonic stem cells. Embryoid bodies were shown to support maturation of the primordial germ cells into haploid male gametes, which when injected into oocytes round off the somatic diploid chromosome complement and develop into blastocysts.
  • Cryobiology
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 1-38
  • View extract

    Summary

    Cryobiology is the core of fertility cryopreservation. The principal application for human fertility cryopreservation began with sperm freezing, and then developed to include embryo and oocyte as well as gonadal cryopreservation. This chapter briefly discusses the scientific background and the current basic knowledge of cryobiology. Aqueous solutions are important for cryobiology since the freezing of biological systems always involves solutions containing substances such as electrolytes, non-electrolytes, polymers, and so on. Some of the classic papers in the field of cryobiology describe the theories and the mechanisms of cryoinjury during cell freezing and thawing. Some cryoprotectants reduce the injury of cells during freezing and thawing. Today, the most commonly used cryoprotectants in the field are glycerol, dimethyl sulfoxide, ethylene glycol, and propylene glycol. Cryoprotectants can interact with each other in a mixture, or with crucial cell molecules, thereby producing effects other than those that would occur with an individual cryoprotectant.
  • 1 - Cryobiology:
  • from Cryobiology
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 1-9
  • View extract

    Summary

    Cryobiology is the core of fertility cryopreservation. The principal application for human fertility cryopreservation began with sperm freezing, and then developed to include embryo and oocyte as well as gonadal cryopreservation. This chapter briefly discusses the scientific background and the current basic knowledge of cryobiology. Aqueous solutions are important for cryobiology since the freezing of biological systems always involves solutions containing substances such as electrolytes, non-electrolytes, polymers, and so on. Some of the classic papers in the field of cryobiology describe the theories and the mechanisms of cryoinjury during cell freezing and thawing. Some cryoprotectants reduce the injury of cells during freezing and thawing. Today, the most commonly used cryoprotectants in the field are glycerol, dimethyl sulfoxide, ethylene glycol, and propylene glycol. Cryoprotectants can interact with each other in a mixture, or with crucial cell molecules, thereby producing effects other than those that would occur with an individual cryoprotectant.
  • Appendix 1 - Autotransplantation of cryopreserved thawed human ovarian tissue
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 257-259
  • View abstract

    Summary

    Oocyte cryopreservation represents an attractive and the least invasive option of fertility preservation strategy for patients wishing to retain their choice of a male partner. Recent advances in vitrification techniques have markedly improved the efficacy of oocyte cryopreservation, demonstrating that vitrification may be more effective than the conventional slow-cooling method. The proposed mechanism of vitrification uses a high concentration of cryoprotectant (CPA) and extremely rapid cooling and warming rates in order to avoid intra-and extracellular ice formation. The commonly used CPAs for cryopreservation of oocytes and embryos are small neutral solutes such as ethylene glycol (EG), 1,2-propanediol (PROH), dimethyl sulfoxide (DMSO), and glycerol. Some devices used for vitrification include the McGill cryoleaf, cryotip, cryotop, nylon loop or cryoloop, thin capillary or open pulled straws, hemi-straws, and electron microscope copper/gold grids. The oocyte vitrification technique offers a realistic hope of fertility preservation for women without partners.
  • Chapter 14 - Cryopreservation of human oocytes: an overview
  • from Section 4 - Cryopreservation of oocytes
  • Edited by Ri-Cheng Chian, McGill University, Montréal, Patrick Quinn
  • Book: Fertility Cryopreservation
  • Published online: 06 July 2010
  • Print publication: 13 May 2010, pp 114-119
  • View extract

    Summary

    An effective oocyte cryopreservation program benefits infertile couples with moral or religious objections about cryopreservation of embryos. When considering all pregnancies and live births obtained from cryopreserved oocytes using the classic slow-freezing method, the survival rates averaged approximately 50%. The percentage of live births per thawed egg ranges from 1 to 10% using the classic slow-freezing protocols. Recently, improved survival and pregnancy rates have been reported using modified slow-freezing procedures, particularly increased sucrose concentration in the suspending solution, and the use of sodium-free freezing solutions. Several attempts have been made with immature human oocytes. Although survival rates seemed to be improved by the slow-freezing method, poor in vitro maturation (IVM) and fertilization are major problems associated with immature egg freezing. Rapid cooling (vitrification) of human oocytes has resulted in relatively higher survival rates. This study suggested that better results can be achieved by vitrifying mature oocytes rather than immature oocytes.

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