Survival of human oocytes cryopreserved with or without the cumulus in 1,2-propanediol

Background Although cryopreservation of human preembryos has been carried out with success, the cryostorage of oocytes, which pose fewer controversial moral, ethical, and legal problems has been much less successful. Various attempts to cryopreserve human oocytes have been mostly unsuccessful and the search for an optimal protocol for oocyte cryopreservation remains elusive. We therefore undertook this study to determine the effect of oocyte cryostorage in 1,2-propanediol.Method Mature human oocytes with or without their cumuli were cryopreserved in precooled 1,2-propanediol, then thawed and inseminated with sperms for in vitro fertilization. The outcome of insemination and subsequent embryonic development were also recorded and compared.Results Postthaw cryosurvival rate was significantly better when cryostorage was carried out with the oocyte cumulus intact as compared to those oocytes denuded of their cumuli (54 versus 27%, respectively; P <0.05). Eight (44%) of 18 surviving postthaw oocytes with intact cumuli were fertilized normally, with cleavage in six, as compared to two (25%) and one, respectively, of those denuded of their cumulus prior to cryostorage. Development to the blastocyst stage was achieved in three embryos derived from oocytes with an intact cumulus at cryostorage. Conclusion We conclude that 1,2-propanediol can be used with success in oocyte cryopreservation, although the issue of parthenogenecity is still to be resolved. Oocyte's with intact cumulus survive cryostorage better than those without it.     

Objective evaluation of the viability of cryopreserved oocytes

Recent studies of fundamental cryobiology, empirical observations and more systematic clinical experiences have generated a renewed interest in oocyte cryopreservation. Poor survival rate has long been the limiting factor which has prevented widespread adoption of oocyte storage. Slow-cooling and vitrification protocols developed in the last few years have apparently solved this problem, ensuring high recovery of viable oocytes from liquid nitrogen storage. However, the definition of oocyte viability appears rather vague. In fact, post-storage survival as assessed on morphological criteria, indicated by the absence of overt cell degeneration, is not necessarily synonymous with viability. Despite its sensitivity to low temperatures, the meiotic spindle can be preserved after cryopreservation and its constitution after thawing can be monitored non-invasively through polarized light microscopy. Assessment of oocyte cryopreservation via clinical parameters is a daunting task. Most studies are small and difficult to interpret because of confounding factors, such as age, patient selection and quality and strategy of use of the cryopreserved material. Some progress has been made, however, as suggested by recent experiences in which the implantation efficiency of embryos produced from thawed oocytes approaches that reported using cryopreserved embryos directly.     

Ongoing pregnancy after intracytoplasmic injection of testicular spermatozoa into cryopreserved human oocytes

Human oocyte cryopreservation has met with limited success in terms of both survival and subsequent fertilization. We recently reported the first birth of a healthy female infant after intracytoplasmic sperm injection of cryopreserved oocytes. The current report describes the first pregnancy achieved after intracytoplasmic injection of testicular sperm into cryopreserved human oocytes.     

Effects of two vitrification protocols on the developmental potential of human mature oocytes

The aim of the present study was to compare an 'open' vitrification protocol to a 'closed' vitrification protocol for mature human oocytes. A prospective comparison between fresh and sibling vitrified oocytes and a retrospective comparison between the two vitrification protocols were performed. For recruited patients undergoing an IVF cycle, two or three fresh oocytes were inseminated with intracytoplasmic sperm injection (ICSI) and the remaining three or more oocytes were vitrified according to manufacturer's instructions with a 'closed' or an 'open' vitrification system. After an unsuccessful fresh cycle, oocytes were warmed and inseminated with ICSI. Embryological parameters were recorded and compared between fresh and sibling vitrified oocytes (intrapatient) as well as between the two vitrification techniques (interpatient). Oocytes vitrified with the 'closed' system showed significantly lower fertilization and cleavage rates and a reduction in the quantity and quality of obtained embryos compared with fresh sibling oocytes (P<0.001). On the contrary, the same parameters were similar between fresh and sibling oocytes vitrified using the 'open' system. The retrospective comparison between the two vitrification protocols also showed a significant increase in clinical pregnancy rate and a reduced proportion of cancelled cycles using the 'open' system (P<0.01).     

Hemizona assay: Use of fresh versus salt-stored human oocytes to evaluate sperm binding potential to the zona pellucida

Salt-stored human oocytes (pH 7.0) showed sperm binding ability equal to that of fresh, living oocytes under hemizona assay (HZA) conditions.     

Co-transfer of embryos derived from cryopreserved and fresh natural cycle oocytes: a pilot study

Italian legislation regarding reproductive medicine prohibits embryo storage while allowing cryopreservation of supernumerary oocytes. This study evaluated the effect of fresh oocytes obtained from natural unstimulated cycles on the clinical success rates derived from the use of frozen-thawed (FR-TH) oocytes obtained following ovarian stimulation. For 36 women, intracytoplasmic sperm injection was performed on FR-TH oocytes supplemented by a fresh oocyte, if available, derived from a natural cycle in which gonadotrophin-releasing hormone-antagonist was used for premature LH surge control. The retrieval rate of fresh oocytes was 61.1% and survival rate of FR-TH oocytes was 43.6%. The fertilization rate of fresh and FR-TH oocytes was 70% and 52.5%, respectively. Fifty embryos were transferred, 14 of them developed from fresh oocytes and 36 from FR-TH oocytes. Six pregnancies occurred in 10 cycles in which the embryos developed from fresh and FR-TH oocytes (pregnancy rate 60.0%) and two in 12 patients in whom the embryos were obtained from only FR-TH oocytes (pregnancy rate 16.7%) (P < 0.05). In summary, the data demonstrate that the transfer of embryos derived from oocytes cryopreserved following a previous ovarian stimulation and an embryo developed from a fresh one retrieved in natural cycle ensures an excellent clinical outcome.     

Qualitative and morphometric analysis of the ultrastructure of human oocytes cryopreserved by two alternative slow cooling protocols

Purpose  

To ascertain possible cell damage from cryopreservation, the ultrastructure of human oocytes cryopreserved by slow cooling was assessed.     

Depoliticize human immunodeficiency virus infection: a commentary

Public-health policy is inconsistent in its approach to the sexually transmitted disease human immunodeficiency virus (HIV). Nearly every health agency has politicized the reporting, finding, and contacting of HIV cases. There is also no consistency among the various state health departments and the various federal health agencies. Until we have a uniform health policy that treats HIV infection as every other reportable sexually transmitted disease, we will make little progress toward controlling its inevitable increase in both cases and costs.     

体外操作对人卵母细胞线粒体膜电位影响的研究

目的 比较体外不同操作对人卵母细胞线粒体膜电位的影响。方法 利用JC-1试剂盒检测人卵母细胞在体外成熟培养、玻璃化冷冻解冻、卵胞质内单精子注射(ICSI)前后的线粒体膜电位变化,从而得出体外不同操作对线粒体膜电位的影响及卵母细胞质量与线粒体膜电位的关系。结果 卵母细胞在体外正常培养成熟、成熟卵母细胞玻璃化冷冻解冻及卵母细胞显微操作过程中线粒体膜电位均无统计学变化(P0.05)。体外成熟培养失败及单精子注射后受精失败的卵母细胞线粒体膜电位有明显下降(P0.05)。结论 体外常规操作对卵母细胞线粒体膜电位并无显著影响,但是线粒体膜电位与卵母细胞质量有密切关系,可以作为检验卵母细胞质量的一个重要指标。     

BFS response to the human fertilisation and embryology authority working group on new developments in reproductive technology: In vitro maturation of oocytes

In 2001 the UK Department of Health initiated the National Occupational Standards Project in Healthcare Science. This project incorporates the 43 disciplines of healthcare science with the aim of developing a framework for competent performance in all areas of healthcare science, thereby standardising the delivery of services in this area. The whole of the project relies on the concept of function, and using the process of functional analysis each discipline is broken down into key work areas. The standards are derived from a further breakdown of these key work areas. Each standard gives expected requirements for the competent performance of the function, along with the relevant knowledge required. It is envisaged that the implementation of National Occupational Standards will ensure that individuals performing healthcare science functions throughout the UK, whether they are healthcare scientists themselves or not, will be performing these functions to an adequate standard. Since work began on the project 63 standards, and associated assessment guidance, have been drafted to cover the whole of healthcare science. The National Occupational Standards are due to be implemented in 2005 by Skills for Health, an organisation that defines and monitors skills in healthcare both in the NHS and the private sector.     

Effect of vitrification on mitochondrial membrane potential in human metaphase II oocytes

Objective

The aim of this study was to evaluate the impact of vitrification on mitochondrial membrane potential (ΔΨm) in human metaphase II (MII) oocytes, and the changes of ΔΨm on thawed MII oocytes.

Methods

MII oocytes were obtained from clinical IVF cycles when the oocytes were failed to fertilization within 24 h after insemination. All oocytes were randomly divided into 4 groups: non-frozen (fresh group), cultured for 0 h (0 h group), 2 h (2 h group) and 4 h (4 h group) after vitrification/thawing. All oocytes were stained with the ΔΨm-specific probe JC-1 and detected by laser scanning confocal microscope (LSCM) for mitochondrial analysis.

Results

The ΔΨm of oocytes was significantly decreased in 0 h and 2 h groups when compared with fresh group (0.93, 1.09 vs 1.34, P < 0.05), but similar between 4 h group and fresh group (1.30 vs 1.34, P > 0.05).

Conclusion

In the vitrification/thawing process, the ΔΨm of MII oocytes could have temporally dynamic changes within 2 h after thawing but would be fully recovered after 4 h culture.