In vitro fertilization: BMA reports on ethics

A summary is provided of the interim ethical guidelines on human in vitro fertilization and embryo replacement issued in May by the British Medical Association. The guidelines approve the therapeutic use of the new techniques. Like the provisional guidelines published last year by the Medical Research Council, they also endorse research on early embryos if the goal of such research is clearly defined and clinically relevant.     

Calcium-releasing activity induced by nuclei of mouse fertilized early embryos

At fertilization,repectitive transient rises of intracellular calcium concentration occur in all mammals studied so far .It has been shown that calcium rises could be induced when mouse fertilized 1-,2-cell nuclei were trans-planted into unfertilized eggs and that the reconstituted embryo could be activated .Howerver,whecther the capability of inducing calcium rises occurs in all stages of mammalian embryos remains unknown ,In this study ,by using the nuclear transplantation technique and measurement of intracellular calcium rises in living cells,we showed that only the nuclei from mouse fertilized 1-cell and 2-cell embryos ,neither the nuclei from 4-,8-cell and ethanol activated parthe-nogenetic embryos nor 2 or 3 nuclei of electrofused 4-cell stage syncytium ,have calcium -releasing activity when they were transferred into unfertilized mature oocytes,Our results indicate that the calcium-releasing activity in nuclei of 1-,2-cell embryos is produced during fertilization and exists at the special stage of fertilized early embryos.These sug-gested that the capacity of inducting calcium release activity in fertilized early embryos is important for normal embryonic development.     

Aberrant DNA methylation in cloned ovine embryos

By using the approach of immunofluorescence staining with an antibody against 5-methylcytosine （5MeC）, the present study detected the DNA methylation patterns of cloned ovine embryos. The embryos derived from in vitro fertilization were also examined for reference purpose. The results showed that： （1） during the preimplantation development, cloned embryos displayed a similar demethylation profile to the fertilized embryos; that is, the methylation level decreased to the lowest at 8-cell stage, and then increased again at morulae stage. However, methylation level was obviously higher in cloned embryos than in stage-matched fertilized embryos, especially at 8-cell stage and afterwards; （2） at blastocyst stage, the methylation pattern in cloned embryos was different from that in fertilized embryos. In cloned blastocyst, inner cell mass （ICM） exhibited a comparable level to trophectoderm cells （TE）, while in in-vitro fertilized blastocyst the methylation level of ICM was lower than that of TE, which is not consistent with that reported by other authors. These results indicate that DNA methylation is abnormally reprogrammed in cloned embryos, implying that aberrant DNA methylation reprogramming may be one of the factors causing cloned embryos developmental failure.     

冷藏雄鼠尸体应用于小鼠运输及意外死亡后品系恢复的可行性

目的 基于小鼠尸体4 ℃冷藏不同时长后精子的体外受精(IVF)效率,探讨低温冷藏小鼠尸体应用于小鼠运输及意外死亡后品系恢复的可行性。方法 实验组为5月龄C57BL/6 J雄鼠,脱颈处死后4 ℃冷藏24、48、72 h和96 h,取附睾尾精子IVF,对照组为正常5月龄C57BL/6 J雄鼠IVF,统计各组IVF受精率。结果 冷藏24 h后附睾尾精子具备正常受精能力,受精率为73.0%、60.0%和77.0%;48 h 组内差异大,受精率为0%、55.4%和3.2%;72 h受精率极低,受精率为3.2%、0%和1.7%;96 h 精子有活力,但无受精能力。所有受精卵均可发育至2细胞,冷藏24 h组和对照组分别移植受体妊娠率分别为60%和66%,证明4 ℃冷藏对胚胎发育无影响。结论 C57BL/6J鼠经4 ℃冷藏的附睾尾,在24 h内具备稳定的受精率,可用于小鼠运输及特殊情况品系恢复。     

小鼠精子微注射受精卵的体外发育与移植的研究

用显微注射方法,将精子注入小鼠卵母细胞卵周隙中,使精卵体外受精获得受精卵。并对精子注射后卵母细胞的成活率、受精率和受精卵的发育率以及移植后受胎率等方面进行了系统的研究,结果表明:卵子存活率为75.36％(1309/1737),其中264枚卵裂,受精率为20·17％(264/1309),卵裂卵经体外培养后有192枚发育到桑椹胚及胚泡期,发育率为72.73％(192/264)。将其中73枚(桑椹胚10枚,肛泡63枚)胚胎移植到10只假孕受体子宫中,一只受体妊娠产仔9只,仔鼠发育正常。     

不同激素对哺乳动物超数排卵作用的研究

本文就PMSG、APMSG、hCG、LHRH等激素对大鼠、小鼠、豚鼠、家兔、绵羊、猪、牛等动物的超数排卵作用进行了系统探索,结果发现PMSGhCG各5～10IU可致小鼠产生稳定的超排、取卵数可达50±10个;用200IU加等量hCG可使大鼠稳定超排,取卵数可达50±10个;用400IUPMSG和等量hCG可使家兔产生稳定起排、取卵数可达35±5个;使用PMSG1500IU和APMSG100IU可使羊产生超排、取卵数可达25±5个：在猪使用1500IUPMSGT和1000IUhCG平均获得卵26±5个;,使用PMSG3000IU和1500IUAPMSG,平均可稳定获得8±12个卵,而在豚鼠得不到稳定起排卵的结果。所有这些结果提示我们PMSG几乎对各种哺乳动物的超排作用显著,且有稳定的剂量可寻,而hCG的促超排也是很显著的。     

Embryo research: British Commons vote for ban

The British House of Commons, overriding opposition by party leaders, approved Enoch Powell's bill which would ban all experiments on human embryos and restrict their use to therapeutic in vitro fertilization procedures. Some members of Parliament have urged the government to announce a timetable for its own, more comprehensive legislation based on the recommendations of the Warnock Committee Report. This action would erode support for Powell's bill, which Lady Warnock warns could end in vitro fertilization in Britain.     

兔卵输卵管培养与再移植后的成活力

本文研究分裂的兔卵在输卵管内培养与再移植。目的是观察这种胚胎的成活力,验证这种方法的实用价值。分裂期的兔卵在输卵管内培养2～3天,发育到胚泡,然后再移植。移植分自体移植和异体移植。总共再移植24例,13例母兔妊娠,产仔9窝,获仔兔21只,怀孕率54.17％,成活率25.61％.     

K~ 和Ca~(2 )对牛体外受精胚胎体外发育的作用

研究观察了在 SOF PVA这一化学成分明确培养系统条件下 ,不同浓度的 K 和 Ca2 对牛体外受精胚胎体外发育的影响 ,以便为今后进一步探讨影响牛早期胚胎体外发育的因素提供实验依据 .实验 1将牛体外受精卵培养分别于含有 0、5 .0、8.3 5和 2 1 .2 m MK 的 SOF PVA培养系统中 ,结果卵裂率分别为 2 0 .0 % a、87.0 % b、80 .8% b和 85 .7% b(ae,P<0 .0 5 ) .实验 2将牛体外受精卵分别培养于含有 0、1 .1 3、1 .71和 3 .0 m MCa2 的 SOF PVA培养系统中 ,结果卵裂率分别为 0 .9% g、86.6% h、80 .9% h 和 92 .0 % h(g相似文献   

热休克诱导三倍体黄鳝的研究

采用热休克诱导方法研究了促使第二极体保留诱发三倍体黄鳝的最佳条件．在卵受精后５－６ｍｉｎ，采用４０．５℃热水处理３．５ｍｉｎ，不但能导致较高的三倍化率，而且胚胎存活率相当高，表明热休克是诱导多倍化的有效方法，需用设备简单，易于推广     

超声波对4种海水鱼类受精卵孵化的影响

采用复合式纵向压电换能器,谐振频率为21．5kHz,谐振阻抗为120Ω,施加电压值为80V的超声波辐射海水鱼类受精卵,研究不同的超声辐射时间和辐射次数对大弹涂鱼、中华乌幅鳢、真鲷和大黄鱼受精卵孵化的影响,结果表明,超声处理大弹涂鱼胚胎发育后期的受精卵,呆提高其孵化率,但对大弹涂鱼和中华乌塘鳢胚胎发育早期受精卵的孵化影响,每次辐射时间为1min、总幅射次数为4次的辐射剂量有利于真鲷受精卵的孵化;每次辐射时间超过1min,孵化率降低,以每次辐射时间为10s或30s处理大黄鱼受精卵,其孵化率分别比对照组高出10％和12％。     

Fertilization potential in golden hamster eggs consists of recurring hyperpolarizations

The fertilization potential, or activation potential, has been demonstrated in the eggs of various species, and it has been shown to block polyspermy in echinoderm, echiuran and frog eggs, but no studies have been reported of electrical phenomena occurring when mammalian eggs are fertilized. We report here the fertilization potential of golden hamster eggs in vitro. To correlate the change of potential with the interaction between sperm and egg, only one sperm was attached to each egg. We found that a sperm induces recurring hyperpolarizations, constituting a fertilization potential which differs from that in the eggs of other species.     

Unborn children (protection) bill

Enoch Powell's Unborn Children (Protection) Bill passed a second reading in the British House of Commons on 22 February 1985. The authors contend that most informed scientists are dismayed because, if enacted into law, the bill would criminalize the in vitro fertilization of any human oocytes except for purposes of "embryo insertion," and many promising avenues of research would be blocked. While the pro-life lobby maintains that the development of possible methods to cure genetic diseases does not require research on human embryos, Evans and McLaren cite scientific data to argue that such research is necessary to insure that embryos chosen for implantation are chromosomally normal, to study the etiology of chromosomal disorders and eventually develop therapies for them, to improve IVF procedures, and to develop new contraceptive techniques.     

Human pregnancy following cryopreservation, thawing and transfer of an eight-cell embryo

The widespread use of clomiphene citrate and exogenous gonadotrophins for in vitro fertilization (IVF) in human frequently results in the production of multiple embryos. Replacement of more than two embryos increases pregnancy rate but may result in multiple pregnancies with increased pre- and post-natal abnormality. Preservation of embryos for a limited time allows fewer embryos to be replaced on several different occasions and thus the problems of multiple pregnancy can be minimized, the effectiveness of a single IVF procedure increased and embryo replacement in adverse maternal conditions avoided. Preimplantation embryos have been successfully cryopreserved in many animal species. The sensitivity of embryos to cooling and freezing varies between species and stages of embryo development. We report here the cryopreservation procedures that allow a high survival rate of four- and eight-cell human embryos and the establishment of a pregnancy following the freezing and storage of an eight-cell embryo for 4 months in liquid nitrogen. The pregnancy terminated at 24 weeks' gestation due to development of a septic Streptomyces agalactiae chorion amnionitis after premature membrane rupture.     

鲈鲤胚胎发育特征观察

观察了水温（18±0．5）℃条件下,鲈鲤[Percocypris pingi pingi（ T chang ）]的胚胎发育特征。结果显示：成熟鲈鲤卵呈球形、桔黄色,为粘性卵,卵径2．2mm,卵膜遇水膨胀后,最大外膜径达3．2-3．8mm。受精卵在水温（18±0．5）℃条件下,受精2h28min后开始第1次卵裂,受精后45h23min开始形成器官,受精后126h28min孵出仔鱼。初孵仔鱼全长为10．4mm,卵黄囊大而侧扁。根据胚胎发育过程的形态特征,可将鲈鲤胚胎发育过程分为受精卵、卵裂、囊胚、原肠胚、神经胚、器官发生和出膜7个连续阶段。32个时期。     

斑马鱼胚胎发育的功能染色体组

随着人类和其他物种染色体组测序工作的完成 ,人类科学最大的任务就是阐明数以万计的基因的生物功能。人类和动物生命周期都从受精卵开始 ,然后一步一步地发育成具有多元组织和器官的生物体。在胚胎形成过程中 ,伴随着基因生成物的协同运作 ,基因按其固有的程序陆续显现出影响 ,从而决定并实现整个人体程序。如果使用适当的动物做模型的话 ,可以加速胚胎功能染色体组的研究。斑马鱼就是这项研究一个很好的模型。斑马鱼最大的优点就是产卵多、体外胚胎发育、体积小、容易养活 ,除此以外 ,很多的分子、细胞、胚胎和基因操作在斑马鱼身上都很容…     

牛体外受精技术研究的现状与展望

系统综述了牛体外受精技术研究的现状及存在的问题．并对今后的研究方向和前景提出了展望。牛卵母细胞可在不含血清的成熟培养液中获得受精及胚胎发育能力，促卵泡素、促黄体素及上皮细胞生长因子均对这一过程具促进作用。肝素是迄今最为有效的精子获能处理方法，但在受精过程中对精子获能起决定作用的是卵丘细胞和卵母细胞本身。提高受精质量可明显提高受精卵的胚胎发育能力。体外受精卵可通过改善培养条件或与体细胞进行复合培养发育到囊胚阶段．但后者更为稳定可靠。目前，牛卵母细胞的体外受精分裂率可达８０％，囊胚发育率达４０％左右．两枚鲜胚的移植妊娠率可达５０％～６０％．而两枚冻胚的移植妊娠率仅３０％～５０％。因此，尚需进一步提高体外受精胚胎的活力和改进胚胎的冷冻保存技术。     

MT—hGH基因注入小鼠受精卵的研究

用显微注射法，将MT－hGH融合基因注入昆明白小鼠受精卵雄原核中，受注的原核卵经体外培养发育的198枚2细胞胚、45枚桑椹胚和161枚胚泡，移植到54只假孕受体，其中16只妊娠产仔只，存活到供试的仔鼠25只，小鼠长到3个月后，切尾制备DNA，经DNA斑点杂交和Southern印迹杂交检测基因整合情况，25只小鼠中3只有融合基因整合，称为转基因小鼠，仔鼠21日龄离乳后饮水中加入锌（Za^ )，以诱导融合基因表达，85日龄时，转基因小鼠体重比对照组重32．0％，还讨论了基因整合方式对胚胎发育的影响。     

Reconstruction of human embryos derived from somatic cells

Reconstruction of human nuclear transfer embryos is a necessary step of therapeutic cloning. In this study we injected somatic cell nuclei into M Ⅱ oocytes and activated reconstructed oocytes with calcium ionophore A23187 (CaA) and 6-dimethylaminopurine (6-DMAP). After oocyteactivation and 2PN formation, we removed the female PN.By using this method, we avoided the application of DNA fluorescent stain and ultraviolet light for oocyte enucleation,and over elimination of ooplasm was also mitigated. Some reconstructed embryos developed into the blastocyst stage in vitro.