小鼠不同卵龄卵母细胞电刺激后第二极体形成和原核发育的研究

实验以强度为０．４５ＫＶｃｍ,持续不同时间（８０、１６０、３２０、６４０μｓ）的电脉冲刺激不同卵龄（注ｈＣＧ后１３、１５、１７、１９小时）小鼠卵母细胞,观察电刺激后第二极体形成和原核发育情况。实验结果说明：（１）卵母细胞守全活化（形成原核）率随卵母细胞也出现ＭⅢ现象,未活化卵母细胞形成第二极体（ＭⅢ）者随卵龄增加而明显增多;（３）电刺激活化小鼠卵母细胞在培养６－９小时之间仍有６．７％形成原核。     

电刺激家兔卵母细胞孤雌活化的研究

采用电刺激使家兔卵母细胞孤雌活化,并对电刺激参数和电刺激介质进行选择,发现在电刺激电压为1.5kV/cm,脉冲持续时间为80us,电刺激3次,电刺激介质为M16的条件下,兔卵母细胞孤雌活化效果最好,可使95％的兔卵母细胞激活,体外培养有89.5％的激活卵发育到正常的8—16细胞期,12％的激活卵发育到囊胚,在体内培养的条件下,26％的激活卵发育到囊胚。采用不同的电刺激介质,卵母细胞最佳激活条件和发育情况不同,表明电刺激介质中Ca~(++)和Mg~(++)浓度似乎与卵母细胞的孤雌活化和维持早期发育有关。家兔在注射LH后17—19小时取卵,电刺激效果最好,激活卵在含细胞松弛素B的培养基中培养3小时,电镜观察已有原核形成,细胞膜附近的细胞器向中央移动。光镜检查表明:约有85％的激活卵具有二个原核,约15％的激活卵有四个原核。     

不同卵龄小鼠卵母细胞激活和受精的比较研究(英文)

本实验比较了不同卵龄的小鼠卵母细胞受酒精人工刺激后的激活率和体外受精率,以探讨卵母细胞激活和受精的机制。向ＮＩＨ雌鼠腹腔注射孕马血清促性腺激素（ＰＭＳＧ）７．５单位,４８小时后注射人绒毛膜促性激素（ＨＣＧ）７．５单位,于不同时间杀小鼠,取卵母细胞与卵丘细胞的复合体（ＯＣＣ）。从注射ＨＣＧ后到取ＯＣＣ的时间视为卵母细胞的卵龄。将ＯＣＣ置于含８％酒精的Ｍ２中７分钟,再在Ｍ１６中培养５小时后,用０．３ｍｇ／ｍＬ的透明质酸酶去卵丘细胞。卵母细胞形成原核或速即卵裂为激活的标志。将ＯＣＣ加入已获能的精子悬液中,５小时后将从卵丘细胞中释放出来的卵母细胞转移到Ｍ１６中,次日发生卵裂为卵母细胞体外受精和激活的标志。小鼠卵母细胞卵龄为２０ｈ,其激活率为８１．６％,速即卵裂率为４８．０％;而卵龄进一步增加到２４ｈ,激活率和卵裂率转为下降（Ｔａｂｌｅ１）。而卵母细胞受精子激活和受精则不同,卵龄为１５ｈ,卵母细胞的体外受精率为４５．４％;随着卵龄的进一步增加,体外受精率则下降（Ｔａｂｌｅ２）。Ｆｉｇ．１显示：新排出的卵母细胞容易被精子激活而受精;卵龄较大的卵母细胞较易被酒精的人工刺激而激活。可能是卵母细胞从成熟到老化过程中,细胞的结     

ROS和丁内酯-Ⅰ抑制山羊卵母细胞的减数分裂

本文研究了ROS（Roscovitine）和丁内酯-Ⅰ（ButyrolactoneⅠ,BL-Ⅰ）两种细胞周期依赖性激酶抑制剂对山羊卵母细胞减数分裂恢复的抑制作用,并研究了抑制对卵母细胞成熟、激活和发育的影响。结果表明：ROS和BL-Ⅰ对山羊卵母细胞减数分裂恢复的抑制作用具有浓度依赖性;200μmol／LROS、100μmol／LBL-Ⅰ、100μmol／LROS＋6．25μmol／LBL-Ⅰ和50μmol／LROS＋25μmol／LBL-Ⅰ都能有效抑制山羊卵母细胞减数分裂的恢复,24h的抑制率分别为78．4％、80．9％、80．3％和77．8％。用ROS和BL-Ⅰ抑制24h后转为正常培养24h,各处理组卵母细胞的成熟率（分别为81．3％、81．9％、83．2％和85．2％）与对照组（83．0％）无显著差异;成熟卵母细胞的化学激活率分别为93．3％、96．2％、92．5％和90．5％,与对照组（97．8％）无显著差异。然而,抑制处理后卵母细胞的卵裂率和桑椹胚率降低,未能发育到囊胚。ROS和BL-Ⅰ抑制山羊卵丘扩展,并且转为正常培养后卵丘不能再扩展。ROS和BL-Ⅰ能够浓度依赖性地抑制山羊卵母细胞减数分裂,二者既可单独,又可降低浓度联合使用,但抑制山羊卵母细胞的浓度远高于牛和猪卵母细胞的;ROS和BL-Ⅰ抑制24h不影响山羊卵母细胞的成熟和激活能力,但影响卵母细胞的卵丘扩展和胚胎发育能力。因此,山羊卵母细胞减数分裂调控可能比它动物更精细。     

不同卵龄小鼠卵母细胞激活和受精的比较研究

本实验比较了不同卵龄的小鼠卵母细胞受酒精人工刺激后的激活率和体外受精率,以探索卵母细胞激活和受精的机制。向NIH雌鼠腹腔注射孕马血清促性腺激素（PMSG）7．5单位,48小时后注射人绒毛膜促性激素（HCG）7．5单位,于不同时间杀小鼠,取卵母细胞与卵丘细胞的复合体（OCC）。从注射HCG后到取OCC的时间视为卵母细胞的卵龄。将OCC置于含8％酒精的M2中7分钟,再在16中培养5小时后,用0．3mg/mL的透明质酸酶去卵丘细胞。卵母细胞形成原核或速即卵裂为激活的标志,将OCC加入已获能的精子悬液中,5小时后将从卵丘细胞中释放出来的卵母细胞转移到M16中,将日发生卵裂为卵母细胞体外受精和激活的标志。小鼠卵母细胞卵龄为20h,其激活率为81．6％,速即卵裂率为48．0％;而卵龄进一步增加到24h,激活率和卵裂率转为下降（Table1）。而卵母细胞受精子激活和受精则不同,卵龄为15h ,卵母细胞的体外受精率为45．4％;随着卵龄的进一步增加,体外受精率则下降（Table2)。Fig.1显示：新排出的卵母细胞容易被精子激活而受精;卵龄较大的卵母细胞较易被酒精的人工刺激而激活。可能是卵母细胞从成熟到老化过程中,细胞的结构、功能及对外界刺激的敏感状态都在发生一些规律性的变化,而激活和受精的机制不完全,还不能精对卵龄的要求要严格。     

家兔胚胎细胞核移植的研究(英文)

本研究以兔为实验材料,对细胞核移植过程中显微操作、电融合、电活化以及移核胚的培养等基本问题进行了研究。对兔进行ＰＭＳＧｈＣＧ超数排卵,收集成熟卵母细胞和１６细胞胚;后者经胰蛋白酶消化,去除胶膜和透明带,在不含Ｃａ２＋、Ｍｇ２＋的分离液中分成单个卵裂球;然后,分别对两者做ＣＢ预处理;首次尝试采用Ｗｉｌａｄｓｅｎ法,去除卵母细胞核、并将单个卵裂球注入透明带,同时、与ＭｃＧｒａｔｈＳｏｌｔｅｒ法进行比较;通过电融合使供体核进入去核的卵母细胞内;将所得移核胚在体外或在中间受体内培养并观察。结果表明：一、Ｗｉｌａｄｓｅｎ法与ＭｃＧｒａｔｈＳｏｌｔｅｒ法比较,核移植操作的成功率及以后的电融合率均无明显差异（Ｔａｂ．１）。相对于后者,Ｗｉｌａｄｓｅｎ法更简便、易于掌握并提高去核率。二、ｈＣＧ超排注射后１３～１５ｈ,观察卵母细胞发现：其中,６７８％保留有第一极体。此时的卵子若去除１／３胞质量,去核率可以达到５８３％。若推迟去核时间,笫一极体退化,失去去核标志。三、比较不同电脉冲条件,发现强度为０６３ｋｖ／ｃｍ,持续１６０μｓ的一次电脉冲可获较高移核胚的融合率（７０．８％）（Ｔａｂ．２）;并可使６１１％的成熟     

斑马鱼卵细胞的体外成熟及成熟卵的受精发育

采用体外培养的方法,研究斑马鱼卵母细胞的成熟过程。Ⅵ时相初级卵母细胞在０．５μｇ／ｍｌ １７ａ－羟基孕酮的ＥＭ－１９９培养液中,８０％氧气,２５℃的体外培养条件下,在４０ｍｉｎ内,胚泡逐渐由卵母细胞中央至动物极边缘１／２处移到动物边缘,进入Ⅴ时相卵母细胞。３０ｍｉｎ后胚泡破裂,胚泡破裂率为５９％,此种卵母细胞继续培养２ｈ才完全成熟,成熟卵不能不滤泡膜中自然排出。冷开水中剥离其外边的滤泡膜后加入具有     

小鼠卵激活过程中胞质游离Ca^2＋的变化及孤雌发育研究

乙醇和电刺激均可使小鼠ＭⅡ期卵母细胞激活并在体外孤雌发育至囊胚。小鼠卵对乙醇十分敏感。用７％－８％乙醇处理５ｍｉｎ后９５％以上的卵母细胞（卵龄为ＨＣＧ注射后１８－１９ｈ）内形成原核。３－４次电刺激后卵的激活率为６３．６３％。乙醇刺激可诱导卵内游离Ｃａ＾２＋浓度出现多次升高;单一电刺激仅能诱导卵内游离Ｃａ＾２＋浓度出现１次升高;多次电刺激可诱导卵内游离Ｃａ＾２＋浓度多次升高,而且电刺激次数与Ｃａ＾２     

蛋白质合成抑制剂亚胺环已酮（CHX）对猪卵母细胞体外成熟的影响

研究了蛋白质合成抑制剂亚胺环已酮（CHX）对猪卵母细胞体外成熟过程中的GVBD、染色质凝集、MⅡ期成熟及卵丘细胞扩展的作用。结果表明：（1）培养液中添加CHX,可抑制卵母细胞GVBD的发生,而且此作用是浓度依赖性的,但CHX的抑效果是完全可逆的;（2）在含10μg/mlCHX液中分别培养0、6、12和24h后转入正常培养液再继续培养至48h,卵母细胞成熟率分别为84．1％、77．1％、48．9％和27．8％;（3）正常培养液中培养0、6、12、24、36和48h后,再转入浓度为10μg/mlCHX液中继续培养至48h,卵母细胞成熟率分别为0、0、0、31．3％、65．4％和79．5％;（4）CHX对卵丘细胞扩展的影响培养时间延长而增强,在CHX中处理时间为16h或更长,完全抑制卵丘细胞的扩展。     

应用氯化锶和放线菌酮对小鼠卵母细胞进行孤雌活化的研究

本试验研究了SrCl_2浓度和作用时间,以及卵龄和蛋白合成抑制剂放线菌酮等对昆明种小鼠卵母细胞活化的影响。研究表明,以含1.6mmol/L SrCl_2的无钙M16液对小鼠卵母细胞活化效果最好(87.0％),显著(P<0.05)优于SrCl_2浓度为1.0、5.0、10.0mmol/L的同种液体。SrCl_2作用时间10分钟显著(P<0.05)好于5、20、30或60分钟。注射hCG后18和20小时卵母细胞的活化率(分别为87.0％和84.6％)显著(P<0.01)高于14或16小时的活化率(分别为4.8％和16.5％)。CHX与SrCl_2联合使用产生显著的协同促进卵母细胞活化作用。     

Electrical activation of mouse oocytes

Activation of the oocyte is the least efficient step in nuclear transplantation in the rabbit. We report the influence of age of oocytes, field strength, pulse duration and number, and shape of field on the rate of activation of mouse oocytes by electrical pulses. Regardless of oocyte age, activation rates were similar over a wide range of field strengths and pulse durations. Aged oocytes activated at a higher rate than recently ovulated oocytes (32 vs 3%), which lysed more frequently (13 vs 2%). Fragmentation rate was also higher among aged oocytes (42 vs 6%). The rate of activation increased with the number of pulses, from 9% with a single pulse, to 61% with six pulses. It also increased with the interval between pulses. Comparison of activation chamber geometries showed that the rate of activation was higher in a nonuniform field than in a uniform field and, for a particular field strength, varied from one electrode gap to another. These observations indicate that the rate of activation can be greatly increased by multiple electrical pulses. The activation rate also varied with consistent field strength in chambers with different electrode configurations.     

化学联合激活可明显提高小鼠孤雌胚胎发育率

为探讨一种高效的小鼠卵母细胞孤雌激活的方案,进一步提高孤雌囊胚发育率。用不同浓度的氯化锶及不同作用时间的乙醇,并分别联合6-DMAP对不同卵龄小鼠卵母细胞进行活化,统计小鼠卵母细胞卵裂率和体外发育状况。结果显示,15～16h、18～19h和20～21h卵龄组卵母细胞经6mmol/LSrCl2联合6-DMAP处理后,三组的激活率随卵龄增长而升高,其中20～21h卵龄组显著高于15～16h、18～19h组(P<0.05),激活胚胎的发育率以18～19h时最高;6mmol/L和10mmol/L的SrCl2联合6-DMAP均能有效地激活小鼠卵母细胞,激活率分别为76.4%和83.6%,桑葚胚率分别为50.0%和56.3%;70ml/L乙醇联合6-DMAP以处理7min组获得了较好的激活率和囊胚发育率,分别为77.1%和42.4%,囊胚率均显著高于4min和10min处理组(P<0.05)。6-DMAP与SrCl2或乙醇联合应用可以有效抑制第二极体的排出,提高激活胚的二倍体比率;孤雌囊胚的平均细胞数显著低于正常受精囊胚(P<0.05)。不同激活方案对孤雌活化胚的核型和发育能力的作用差异较大,小鼠卵母细胞孤雌激活率与卵龄...     

Repetitive calcium stimuli drive meiotic resumption and pronuclear development during mouse oocyte activation.

Freshly ovulated (12 hr post hCG) F1 (C57BL/6 x CBA) hybrid mouse oocytes were parthenogenetically activated by repetitive elevation of Ca2+ induced by carefully controlled electrical pulses. Different patterns of stimulation were employed to examine the role of repetitive calcium changes on meiotic resumption and pronuclear development. In the first series of experiments oocytes received 33 electrical pulses of 1.8 kV/cm delivered every 4 min. The pulse duration decreased according to a negative exponential equation from a 900-microseconds first pulse to give a total pulse duration of 18.721 msec. The strength of calcium stimuli was varied by changing the concentration of CaCl2 in the medium. Ninety-eight percent of the oocytes stimulated with 12 microM calcium extruded the second polar body by the end of treatment and 92% completed pronuclear formation between 3.5 and 8 hr after the first pulse. For higher or lower Ca2+ concentrations the proportion of oocytes developing pronuclei decreased; the timing of pronuclear formation was retarded and the majority of oocytes failed to form a pronucleus after extrusion of the second polar body. In the second series of experiments, the strength of the calcium stimuli was modulated by changing the duration of the 33 electrical pulses given in the presence of 12 microM calcium. By increasing the total pulse duration to 33.958 msec, 100% of the oocytes activated and completed pronuclear formation between 3 and 5 hr after the first electric pulse. Stimulation protocols of lower total pulse duration (less than 18.721 msec) gave rise to high rates of partial activation (up to 95%). Examination of these partially activated oocytes showed metaphases with haploid sets of chromatids characteristic of third meiotic metaphase arrest. The results indicate that repetitive calcium stimuli can regulate the rate and extent of meiotic resumption and the time course of pronuclear formation during mouse oocyte activation. They suggest that meiotic resumption in mammalian oocytes is regulated by the amplitude and frequency of cytosolic calcium oscillations induced by the activating stimulus.     

Parthenogenetic activation of mouse oocytes by exposure to strontium as a source of cytoplasts for nuclear transfer

Cell-cycle phase of the donor and recipient cells at the moment of nuclear transfer influences subsequent development of the reconstituted embryo. In order to study this effect, the precise cell-cycle phase of the recipient oocyte at the time of fusion must be known and this depends on reliable activation of oocytes in a protocol that has a low incidence of spontaneous activation. Mouse oocytes recovered before (8-10 hours post-human chorionic gonadotropin [hCG]) and after ovulation (14 and 18 hours post-hCG) were exposed to strontium ions in calcium magnesium-free M16 culture medium. The effect on development of haploid parthenotes of post-hCG age of the oocyte, the duration of exposure, and strontium concentration in the medium was determined. These experiments established a reliable method of parthogenetic activation of recently ovulated mouse oocytes, involving the culture of oocytes for 60 minutes in 25 mM strontium in a calcium magnesium-free M16 medium. This method of activation was also able to induce activation of preovulatory oocytes after a preincubation period in vitro. Only a low incidence of spontaneous activation was observed if oocytes were recovered before or immediately after ovulation (14 hours after hCG).     

Morphology of porcine cumulus-oocyte-complexes depends on the stage of preovulatory maturation

The aim of this investigation was to determine the relationship between the morphology of the cumulus-oocyte-complexes (COCs) and the meiotic configuration of oocytes as an LH peak mimicked by hCG. Estrus was synchronized in a total of 29 crossbred Landrace gilts by feeding Regumate for 15 d and administering 1000 IU PMSG. The LH peak was simulated by treatment with 500 IU hCG at 80 h after PMSG. Endoscopic oocyte recovery was carried out 2 h before and 10, 22 and 34 h after hCG. Only macroscopically healthy follicles with a diameter of more than 5 mm were punctured. Altogether, 410 follicles from 57 ovaries were punctured and 251 COCs were aspirated. Oocyte recovery rate increased from 48.5% (P < 0.01) of the early, not yet preovulatory follicles (2 h before hCG) to 80.8% of late preovulatory follicles (34 h after hCG). Cumulus morphology in COCs recovered 2 h before and 10 h after hCG was heterogeneous, with most (72.9 to 57.4%; P < 0.01) showing a compact or slightly expanded cumulus. Starting at about 22 h after hCG, COC morphology changed dramatically (86.7% of COCs with expanded cumulus; P < 0.01), and 34 h after hCG, 98.3% of the COCs had only an expanded cumulus. The percentage of oocytes with a mature meiotic configuration increased (11.2; 7.1; 41.4 and 70.2%, respectively, n = 238 oocytes; P < 0.01) as the interval post hCG increased (-2, 10, 22, 34 h, respectively). Meiotic configuration was related to COC morphology: compact COCs--88.9% diplotene, expanded COCs--53.8% metaphase II (M-II), and denuded oocytes--69.2% degenerated chromatin. These results indicate that there is a relationship between oocyte recovery rate, COC morphology, and meiotic configuration and preovulatory follicle maturation after the application of hCG.     

不同因素对大鼠卵母细胞孤雌激活作用影响的研究

本实验比较了SrCl_2,放线菌酮(CHX),电刺激和乙醇等理化因素对SD大鼠卵母细胞激活的作用。结果表明,SrCl_2,CHX和电刺激均能有效激活SD大鼠卵母细胞,其最高激活率分别达到93.24％,91.89％和85.90％。8％乙醇对注射hCG 21小时后的卵母细胞激活率也达70％。SrCl_2在1.6和3.2mmol/L浓度,作用10—30分钟均有较好激活效果。电刺激强度在160V,80μs作用较佳。当SrCl_2与CHX联合作用时,激活率可有明显提高。但电刺激或乙醇与CHX的联合作用不能有效提高激活 率。本研究还比较了卵丘细胞的存在与否对激活的影响,发现卵丘-卵母细胞复合体中的卵母细胞不能被有效激活。刚离体的超排卵母细胞也不能被有效激活,须在体外培养一定时间后才能被激活。     

Role of Na+/Ca2+ Exchanger (NCX) in Modulating Postovulatory Aging of Mouse and Rat Oocytes

We studied the role of the Na⁺/Ca²⁺ exchanger (NCX) in modulating oocyte postovulatory aging by observing changes in NCX contents and activities in aging mouse and rat oocytes. Whereas the NCX activity was measured by observing oocyte activation following culture with NCX inhibitor or activator, the NCX contents were determined by immunohistochemical quantification. Although NCX was active in freshly-ovulated rat oocytes recovered 13 h post hCG injection and in aged oocytes recovered 19 h post hCG in both species, it was not active in freshly-ovulated mouse oocytes. However, NCX became active when the freshly-ovulated mouse oocytes were activated with ethanol before culture. Measurement of cytoplasmic Ca²⁺ revealed Ca²⁺ increases always before NCX activation. Whereas levels of the reactive oxygen species (ROS) and the activation susceptibility increased, the density of NCX member 1 (NCX1) decreased significantly with oocyte aging in both species. While culture with H₂O₂ decreased the density of NCX1 significantly, culture with NaCl supplementation sustained the NCX1 density in mouse oocytes. It was concluded that (a) the NCX activity was involved in the modulation of oocyte aging and spontaneous activation; (b) ROS and Na⁺ regulated the NCX activity in aging oocytes by altering its density as well as functioning; and (c) cytoplasmic Ca²⁺ elevation was essential for NCX activation in the oocyte.     

Pregnancies and live birth from in vitro fertilization of calf oocytes collected by laparoscopic follicular aspiration

Oocytes were recovered by laparoscopic aspiration from 3- to 8-week-old calves treated with follicle-stimulating hormone (FSH) followed by human chorionic gonadotropin (hCG) to induce follicular growth and oocyte maturation in vivo. Most of the recovered oocytes either had resumed meiotic maturation at the time of aspiration or were competent to undergo maturation during subsequent culture in vitro. Oocytes matured in vivo following FSH and hCG treatment underwent in vitro fertilization (70%) at rates not significantly different from those of control oocytes recovered from adult cow ovaries at abattoirs and matured in vitro (75%). Calf oocytes that were immature at aspiration exhibited lower fertilization rates after in vitro maturation (36%) but their rate of development to morulae and blastocysts did not differ from that of mature oocytes at aspiration. A total of 91% of the zygotes produced from calf oocytes developed to morula and 27% to blastocyst stages during 6 days of culture. The proportion developing to morulae was significantly higher (P<0.05) than that observed for zygotes resulting from in vitro maturation and fertilization of oocytes recovered from cow ovaries obtained at an abattoir and processed concomitantly (59% to morulae and 18% to blastocysts). Morulae or blastocysts developed from oocytes from 5 to 6-week-old calves, when transferred to synchronized recipient heifers, resulted in 2 confirmed pregnancies, one of which produced a single full-term live calf. The ability to produce embryos from oocytes recovered from newborn or prepubertal calves offers the potential for markedly reducing the generation interval in cattle, thereby substantially accelerating the rate of genetic gain that can be achieved through embryo transfer.     

Influence of sequence duration and number of electrical pulses upon rabbit oocyte activation and parthenogenetic in vitro development

Electroactivation of in vivo mature young rabbit oocytes was investigated here. The effects of four or eight electrical pulse treatment over 90, 150 or 270 min upon oocyte activation frequency and type, and even upon their subsequent in vitro development, were studied. The lowest activation frequency was observed after applying four-pulses over 90 min (54%). However, extending four-pulse treatment duration over 150 or 270 min induced more oocytes to activate (from 84% to 100%), as did the eight pulsing treatments (from 91% to 97%). With eight pulses, extending treatment duration improved the normal activation rates (from 47% to 76%; P<0.05). Nevertheless, the haploid morulae and blastocyst rates decreased significantly with extended eight pulsing treatment duration (morulae: from 94% to 41% and blastocysts: from 31% to 0%).