Hammitt D G, Syrop C H, Walker D L, Bennett M R
Department of Obstetrics and Gynecology, University of Iowa Hospitals and Clinics, Iowa City.
Fertil Steril. 1993 Jul;60(1):131-6. doi: 10.1016/s0015-0282(16)56050-6.
To examine differences in sperm binding to the zona and recovery of oocytes from the storage vessel after oocyte preservation for the hemizona assay (HZA) by the method currently in predominant use, salt storage at 4 degrees C, as compared with a new method that should allow for indefinite preservation of zona receptors, dimethylsulphoxide (DMSO)/sucrose in liquid nitrogen (-196 degrees C). A second objective was to compare sperm binding to noninseminated zona as opposed to zona from inseminated, nonfertilized oocytes and to examine whether differences in binding potential were related to the patient's fertilization rate from the cycle in which the oocytes for the HZA originated.
Binding and recovery were evaluated after 1, 2, 3, 6, 9, 12, and 17 to 25 months of storage.
In vitro fertilization and andrology laboratories at the University of Iowa Hospitals and Clinics; academic tertiary care center.
Binding of sperm was significantly lower for nonfertilized oocytes stored > 12 months in salt at 4 degrees C than for those stored in liquid nitrogen. Binding was similar after storage for 1, 2, 3, 6, 9, and 12 months. Oocyte recovery was significantly lower after storage in salt for > 12 months as compared with storage in liquid nitrogen. Greater variability in sperm binding was observed between matching zona halves of nonfertilized as compared with noninseminated oocytes. Nonfertilized oocytes also bound fewer total sperm than noninseminated oocytes. The number of sperm bound to noninseminated oocytes was not related to the patient's fertilization rate from the cycle in which the oocytes originated. However, significantly fewer sperm bound to the zona of nonfertilized oocytes when the oocyte originated from a cycle in which the patient's fertilization rate was > 50%.
These results indicate that storage of oocytes in DMSO/sucrose in liquid nitrogen results in superior long-term (> 12 months) preservation of zona receptors for sperm binding and improves oocyte recovery as compared with salt storage at 4 degrees C. Although noninseminated oocytes appear to be optimal for use in the HZA, nonfertilized oocytes can be used successfully if the oocytes originate from an IVF cycle in which the fertilization rate is < or = 50%.
通过目前主要使用的方法（4℃盐储存）与一种新方法（二甲基亚砜（DMSO）/蔗糖液氮（-196℃）储存，该方法应能无限期保存透明带受体），研究卵母细胞保存用于半透明带分析（HZA）后，精子与透明带结合的差异以及从储存容器中回收卵母细胞的情况。第二个目的是比较精子与未受精卵母细胞的透明带和已受精但未着床卵母细胞的透明带的结合情况，并研究结合潜能的差异是否与HZA所用卵母细胞来源周期中患者的受精率有关。
在储存1、2、3、6、9、12以及17至25个月后评估结合和回收情况。
爱荷华大学医院及诊所的体外受精和男科学实验室；学术三级医疗中心。
4℃盐储存超过12个月的未受精卵母细胞，其精子结合率显著低于液氮储存的卵母细胞。储存1、2、3、6、9和12个月后，结合情况相似。与液氮储存相比，盐储存超过12个月后卵母细胞回收率显著降低。与未受精卵母细胞相比，未受精卵母细胞匹配的半透明带之间精子结合的变异性更大。未受精卵母细胞结合的精子总数也少于未受精的卵母细胞。与未受精卵母细胞来源周期中患者的受精率无关。然而，当卵母细胞来自患者受精率>50%的周期时，与未受精卵母细胞透明带结合的精子明显减少。
这些结果表明，与4℃盐储存相比，将卵母细胞储存在液氮中的DMSO/蔗糖中可使精子结合的透明带受体得到更好的长期（>12个月）保存，并提高卵母细胞回收率。虽然未受精的卵母细胞似乎是HZA的最佳选择，但如果卵母细胞来自受精率≤50%的体外受精周期，未受精的卵母细胞也可成功使用。
