Consequences of Nitric Oxide Synthase Inhibition During Bovine Oocyte Maturation on Meiosis and Embryo Development

The importance of nitric oxide synthase (NOS) in bovine oocyte maturation was investigated. Oocytes were in vitro matured with the NOS inhibitor N^w- l -nitro-arginine methyl-ester (10⁻⁷, 10⁻⁵ and 10⁻³  m l -NAME) and metaphase II (MII) rates and embryo development and quality were assessed. The effect of l -NAME (10⁻⁷  m ) during pre-maturation and/or maturation on embryo development and quality was also assessed. l -NAME decreased MII rates (78–82%, p < 0.05) when compared with controls without l -NAME (96%). Cleavage (77–88%, p > 0.05), Day 7 blastocyst rates (34–42%, p > 0.05) and total cell numbers in blastocysts were similar for all groups (146–171 cells, p > 0.05). Day 8 blastocyst TUNEL positive cells (3–4 cells) increased with l -NAME treatment (p < 0.05). For oocytes cultured with l -NAME during pre-maturation and/or maturation, Day 8 blastocyst development (26–34%) and Day 9 hatching rates (15–22%) were similar (p > 0.05) to controls pre-matured and matured without NOS inhibition (33 and 18%, respectively), while total cell numbers (Day 9 hatched blastocysts) increased (264–324 cells, p < 0.05) when compared with the controls (191 cells). TUNEL positive cells increased when NOS was inhibited only during the maturation period (8 cells, p < 0.05) when compared with the other groups (3–4 cells). NO may be involved in meiosis progression to MII and its deficiency during maturation increases apoptosis in embryos produced in vitro . Nitric oxide synthase inhibition during pre-maturation and/or maturation affects embryo quality.     

体外成熟对牛卵母细胞孤雌激活后发育潜力的影响

本试验在卵母细胞体外成熟的研究基础上,研究了培养用水、卵泡液和成熟时间对卵母细胞体外成熟及孤雌激活后发育潜力的影响.结果表明(1)将卵母细胞分别于蒸馏水和Milli-Q超纯水配制的成熟培养液中培养22～24 h, 孤雌激活后, 卵裂率无显著差异(P>0.05); 但孤雌卵在超纯水配制的胚胎培养液中培养,囊胚发育率为22.3%, 明显高于在蒸馏水配制的培养液中的囊胚发育率14.1%(P<0.05).(2)在成熟培养液中添加10%、20%卵泡液,成熟卵母细胞孤雌激活后的囊胚发育率(32.3%, 30.9%)明显高于添加5%和0%卵泡液组的囊胚发育率(21.8%, 22.7%,P<0.05).卵母细胞在添加20%卵泡液的培养液中成熟培养,孤雌激活后囊胚孵化率明显低于添加0、5%、10%卵泡液组的囊胚孵化率(P<0.05).(3)成熟28 h或30 h的卵母细胞孤雌激活后,其囊胚发育率(30.5%或29.4%)明显高于成熟24 h或26 h组的囊胚发育率(20.5%或22.1%,P<0.05).     

牛卵母细胞体外成熟、体外受精及胚胎培养的研究

以牛卵母细胞为试验材料,研究了不同温度、不同运送时间对牛卵母细胞成熟的影响,比较自配成熟培养液与IVMD101成熟培养液对牛卵母细胞发育的影响,也进行了孤雌激活和体外受精在相同培养条件下对牛卵母细胞胚胎发育的影响比较.结果表明:卵巢在37～42℃运输后的成熟率(11.3%)明显低于20～30℃、30～37℃(79.3%、85.1%),20～30℃、30～37℃组间差异不显著(P>0.05);运送6 h后的卵母细胞成熟率(53.2%)明显低于4 h内、4～6 h(85.6%、77.8%),4 h内、4～6 h组间差异不显著(P>0.05);自配成熟液与IVMD成熟液相比,体外成熟率(89.03%、88.89%)、卵裂率(71.73%、74.53%)、8细胞率(62.35%、72.05%)和囊胚率(22.94%、21.18%)均无显著差异(P0.05).     

葡萄糖在牛体外受精及胚胎发育中的影响

在牛精子获能液中添加不同浓度的葡萄糖,应用体外培养技术对牛精子体外获能及早期胚胎发育进行研究,通过观察顶体反应、超激活、活率和早期胚胎发育率,筛选出获能液中最适葡萄糖浓度及其有利于牛早期胚胎发育的最佳浓度.结果表明:葡萄糖是精子获能和维持超激活运动的主要能源物质,其代谢过程中产生的活性氧在牛精子体外获能、受精过程中起重要作用,高浓度(超过9.15 mM)葡萄糖有利于获能的完成;但是对早期胚胎发育不利,对早期胚胎发育来说其最适添加量为6.10 mM,此时的囊胚率最高.     

换液培养对猪卵母细胞的成熟及胚胎体外发育的影响

通过后期去除激素培养比较了卵丘卵母细胞成熟及构建克隆胚后的发育情况,同时孤雌胚胎和体外受精胚胎体外培养48 h后全量换液,比较了其卵裂率和囊胚率之间的差异。结果显示,卵丘卵母细胞培养22h后换成不含激素的成熟培养液继续培养至44 h,其成熟率与对照组无显著差异(P0.05);后期克隆胚胎卵裂率和囊胚率与对照组均无显著差异(P0.05)。孤雌胚胎换液培养卵裂率高于未换液组,囊胚率低于未换液组,但差异均不显著(P0.05)。体外受精胚胎换液培养卵裂率以及囊胚率和未换液组差异不显著(P0.05)。本实验结果说明换液培养对卵母细胞的成熟及后续的体细胞克隆胚发育无显著影响,孤雌和体外受精胚胎换液培养对后期发育也无显著影响。     

Effect of Antioxidants During Bovine In Vitro Fertilization Procedures on Spermatozoa and Embryo Development

Increased amounts of reactive oxygen species (ROS) during in vitro fertilization (IVF) may cause cytotoxic damage to gametes, whereas small amounts of ROS favour sperm capacitation. The aim of this study was to investigate the effect of antioxidants [50 μ m β-mercaptoethanol (β-ME) and 50 μ m cysteamine (Cyst)] or a pro-oxidant (5 m m buthionine sulfoximine) on the quality and penetrability of spermatozoa into bovine oocytes and on the subsequent embryo development and quality when added during IVF. Sperm quality, evaluated by the integrity of plasma and acrosomal membranes, and mitochondrial function, was diminished (p < 0.05) after 4-h culture in the presence of antioxidants. Oocyte penetration rates were similar between treatments (p > 0.05), but antioxidants adversely affected the normal pronuclear formation rates (p < 0.05). The incidence of polyspermy was high for β-ME (p < 0.05). No differences were observed in cleavage rates between treatments (p > 0.05). However, the developmental rate to the blastocyst stage was adversely affected by Cyst treatment (p < 0.05). The quality of embryos that reached the blastocyst stage, evaluated by total, inner cell mass (ICM) and trophectoderm cell numbers and ICM/total cell ratio was unaffected (p > 0.05) by treatments. The results indicate that ROS play a role in the fertilizing capacity in bovine spermatozoa, as well as in the interaction between the spermatozoa and the oocytes. It can be concluded that supplementation with antioxidants during IVF procedures impairs sperm quality, normal pronuclear formation and embryo development to the blastocyst stage.     

生物频谱对牛胚胎体外生产效率的影响

本试验利用可调式周林生物频谱发生器对牛卵母细胞体外成熟、体外受精和体外培养过程实施辐射 ,以提高牛胚胎体外生产效率。频谱发生器与培养材料的距离为 5cm ,辐射强度根据辐射温度加以调节。实验结果表明 ,辐射温度控制在 39℃时 ,入孵卵母细胞的卵裂率 ( 63% )与对照组 ( 61 % )无显著差异(P >0 0 5) ,而囊胚发育率 ( 39% )显著高于对照组 ( 1 9% ) (P <0 0 5) ;当辐射温度达到 4 0℃时 ,实验组的卵裂率仅为 1 4 % ,囊胚率为 0。体外受精生产的囊胚用EFS4 0液进行玻璃化冷冻保存 ,解冻后发现 ,整个生产过程经生物频谱辐射胚胎的体外发育率 ( 86% )显著高于对照组 ( 65% )。     

季节对绵羊卵母细胞体外成熟及胚胎发育能力的影响

试验采用梯度LH与E2的作用浓度比较卵母细胞的体外成熟率,并采用添加7.0μg/mLLH、1.3μg/mLE2研究季节性对绵羊卵母细胞体外成熟及胚胎发育能力的影响。结果表明:①LH与E2的作用浓度对非繁殖季节(5月)卵母细胞成熟率影响差异不显著(P>0.05),但以添加LH7.0μg/mL、E21.3μg/mL组卵母细胞成熟率较好。②LH与E2的作用浓度对繁殖季节(12月)卵母细胞成熟率影响差异不显著(P>0.05),以LH10.0μg/mL与E21.3μg/mL时卵母细胞成熟率较好。③湖羊和其他季节性发情绵羊卵母细胞的成熟率在繁殖季节(72.08%vs69.82%)与非繁殖季节(67.89%vs65.79%)差异不显著(P>0.05),但以繁殖季节的成熟率较高。④湖羊的卵母细胞在非繁殖季节与繁殖季节胚胎卵裂率(72.28%vs75.43%)、桑葚胚率(36.14%vs34.97%)差异不显著(P>0.05),繁殖季节囊胚率比非繁殖季节囊胚率偏高(16.18%vs14.40%)。     

牛体外受精胚胎的体外培养研究进展

家畜体外受精（IVF）技术自上世纪八十年代获得成功以来，发展十分迅速，九十年代已进入试管胚的开发应用阶段。目前，IVF胚胎的质量与体内胚相比仍有很大差距。在进行IVF胚胎体外培养时，常会出现“体外发育阻断”现象，主要表现为细胞数较少、卵裂球形状不规则、存在死亡的细胞和细胞质碎片、发育速率和抗冻性降低以及酶活性和营养物摄取的改变等方面。近年来，为了克服胚胎体外发育所存在的某些缺陷，国内、外对不同动物的胚胎体外培养体系和培养方法进行了系统研究，取得了长足进展。本文就牛IVF胚胎体外培养方面的研究进展综述如下。     

Effect of Days Post-Partum, Breed and Ovum Pick-Up Scheme on Bovine Oocyte Recovery and Embryo Development

The objective of this study was to investigate (i) the effect of two different ovum pick-up (OPU) schemes (once vs twice weekly aspirations) on oocyte recovery rate, quality and subsequent in vitro embryo development, (ii) the influence of days post-partum on oocyte recovery and (iii) possible differences in OPU results from two different herds. In group A, OPU was performed twice weekly in two Holstein Friesian (HF) and three Danish Red and White (DRW) cows from a private herd. In the research herd, two groups of eight HF cows were investigated: group B (OPU once weekly) and group C (OPU twice weekly). The collected oocytes were subsequently submitted to in vitro embryo production. More oocytes were recovered from the private herd when compared with the research herd. In the research herd, the twice weekly scheme aspirated more oocytes than the once weekly scheme. The quality of the retrieved oocytes was significantly different between groups B and C but not between groups A and C, and HF cows yielded higher quality oocytes than DRW cows (p = 0.029). Oocytes from group C showed higher level of embryonic development than group B oocytes. No differences in blastocyst rates were observed between groups A and C. Session affected the number of retrieved oocytes and subsequent developmental rates, with these being lower in the first compared with the last sessions. Finally, there was no significant effect of days post-partum in the number and quality of the retrieved oocytes, likely because of the small group size and high variation between sessions.     

Effects of Addition of Tissue‐Type Plasminogen Activator in In Vitro Fertilization Medium on Bovine Embryo Development and Quality

Plasminogen activators/Plasmin system plays pivotal role in regulating reproductive functions of mammals. Here, we examined the effects of modification of in vitro fertilization medium (IVF medium) with the addition of tissue‐type plasminogen activator (t‐PA), on bovine embryo development and quality, assessed by quantification of expression of various genes related to metabolism, oxidation, implantation and apoptosis. In addition, plasminogen activator activity (PAA) and plasminogen activator inhibition (PAI) were measured in the spent media. After conventional IVM, 2016 cumulus‐oocyte complexes (COCs) were divided into four groups with modified composition of the IVF medium containing t‐PA and/or its inhibitor epsilon‐aminocaproic acid (control, t‐PA, t‐PA+ε‐ACA, ε‐ACA). Presumptive zygotes were cultured for 8 days in synthetic oviductal fluid (SOF) medium; gene expression studies were carried out on morulae and blastocysts. t‐PA alone significantly suppressed cleavage and blastocyst formation rates, but this effect was neutralized by the addition of ε‐ACA. PAA in the treated group was significantly reduced by ε‐ACA, but without total elimination. Significant differences were detected in the expression of genes related to apoptosis and/or cell cycle arrest (BAX, BCL2L1, KAT2B) between embryos produced in t‐PA‐modified media and controls, giving an overall notion that the inferior developmental competence of treated embryos may be attributed to apoptotic phenomena induced by t‐PA. In conclusion, it appears that excessive t‐PA content in the IVF media, suppresses blastocyst formation rate, possibly due to induction of apoptotic phenomena.     

The Effects of Blastomere Biopsy and Oxygen Tension on Bovine Embryo Development, Rate of Apoptosis and Interferon-τ Secretion

A series of experiments was performed to examine the effects of blastomere biopsies on subsequent development of IVF-derived bovine embryos. The first experiment was designed to assess the optimal time for blastomere removal. One blastomere was removed either 48 or 72 h after IVF. Biopsy at 48 h resulted in 17.2% of embryos proceeding to the blastocyst stage, which was lower than when biopsies were performed at 72 h (37.5%, p < 0.05). In the second experiment, embryos were cultured either under atmospheric or 5% O(2) following blastomere removal. Biopsies had no effect on rate of blastocyst formation with 36% of controls and 33.7% of biopsied embryos proceeding to that stage. However, culture under 5% O(2) significantly increased the number of blastocysts from 29.9% to 40.3% (p < 0.05). This effect was significant in both biopsied and control embryos. In the final experiment, biopsied embryos were again cultured under different oxygen tension. Blastocysts were collected and cultured individually for 48 h in medium droplets in their respective O(2) concentration after which time the medium was assayed for concentration of interferon-tau (IFN-tau). Reduced O(2) concentration again significantly increased blastocyst formation from 24.9% to 41.9% (p < 0.05). IFN-tau secretion was not affected by biopsies, but culture under atmospheric O(2) resulted in significantly increased IFN-tau concentration in medium droplets (12274.0 +/- 2825.9 pM vs 5046.5 +/- 2562.2 pM; p < 0.05).     

Effects of Serum-Free In Vitro Maturation of Bovine Oocytes on Subsequent Embryo Development and Cell Allocation in Two Developmental Stages of Day 7 Blastocysts

Maturation of oocytes and the subsequent outcome of the in vitro production (IVP) are affected by the composition of in vitro maturation (IVM) medium. To determine the use of serum interfering with effects of single molecules, we aimed at developing simplified IVM medium. The experimental IVM media were: (1) M199-medium supplemented with hormones and serum (control), (2) as 1 but serum was substituted with fatty acid-free serum albumin (FAFBSA) and (3) M199-medium without hormonal and serum supplementation (M199). The quality of embryos was assessed on day 7 by morphology and cryotolerance, as well as by Terminal deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling (TUNEL) and differential staining. Results showed that the nuclear maturation was suppressed in M199 group alone. Embryo cleavage and development rates, and the proportion of quality 1 blastocysts were lower in the FAFBSA and M199 groups compared to the control. Differences in the cell allocation of fresh embryos were observed at the blastocyst stage, but not at the expanded blastocyst stage. The control group blastocysts had larger number of cells allocated to the inner cell mass (ICM), and the FAFBSA group blastocysts larger apoptotic cell proportion compared to the blastocysts derived from other groups. After cryopreservation, the reduction of ICM proportion and increase of apoptotic cell proportion of embryos were equal between the experimental groups. In conclusion, exclusion of serum from the IVM media reduces embryo development and may cause perturbations in blastocyst development. Differences in the cell allocation of blastocysts between IVM media may appear only when the developmental stages are taken into account.     

水牛卵丘细胞和颗粒细胞单层对卵母细胞体外受精及其胚胎发育的影响

[目的]探讨卵丘细胞对水牛卵母细胞体外成熟、体外受精及颗粒细胞单层对水牛体外胚胎发育的影响。[方法]①按卵母细胞有无卵丘细胞情况分为五个组：即自然裸卵组（Ⅰ组）、自然裸卵＋卵丘细胞共成熟组（Ⅱ组）、人为裸卵＋卵丘细胞共成熟组（Ⅲ组）、AB级卵母细胞成熟后去除卵丘细胞受精组（Ⅳ组）、AB级卵母细胞对照组（Ⅴ组）分别进行体...     

牛体外受精的精子获能方法对受精率和胚胎发育的影响

从屠宰场获得牛卵巢,采取卵母细胞,成熟培养用ＴＣＭ１９９＋犊牛血清;精子获能处理,以ＢＯ液＋肝素钠为基础,三个试验组分别添加咖啡因、蔡碱和已酮可可碱,受精经分别为８１．３％、８３．３％、８８．９％,均显著高于对照组（Ｐ〈０．０１）,三个试验组的囊胚率分别为２０．４％、１９．３％、２１．２％。试验得出以下结论：囊胚率与受经成正比,添加已酮可要碱效果最好。另外组内种公牛成绩也有差异。     

屠宰牛卵母细胞体外成熟和体外受精研究

对采集到的卵巢采取抽吸法、割破法回收卵母细胞,割破法得到的A级卵母细胞显著高于抽吸法。把有黄体和无黄体的卵巢卵母细胞进行培养比较,无黄体的卵巢卵母细胞的成熟率为84．33％,显著高于有黄体卵巢卵母细胞的74．32％。本试验中卵泡卵母细胞和深层卵母细胞体外成熟率均能达到75％以上．卵巢表面卵泡卵母细胞的卵裂率为54．76％,高于深层卵母细胞的卵裂率,但二者无显著差异。IVM时添加卵丘细胞、IVC时添加输卵管上皮细胞是比较理想的培养系统。     

Effect of Alpha-Tocopherol and Ascorbic Acid on Bovine Oocyte in Vitro Maturation

In vitro culture results in higher oxygen concentrations than in vivo environments, leading to an increased level of reactive oxygen species (ROS) that cause lipid peroxidation of cellular membranes. Alpha-tocopherol (active form of vitamin E) is an antioxidant that protects mammalian cells against lipid peroxidation, which is regenerated by ascorbic acid. The aim of this study was to determine the effect of the addition of alpha-tocopherol and/or ascorbic acid to the maturation medium on bovine oocyte in vitro maturation (IVM) and subsequently on in vitro fertilization (IVF) and embryo development. Cumulus-oocyte complexes (COCs) were matured in Medium 199 (control), and with the addition of alpha-tocopherol and/or ascorbic acid. The concentration of alpha-tocopherol in COCs was determined by high-performance liquid chromatography (HPLC). IVF and in vitro culture (IVC) were carried out in modified synthetic oviductal fluid (mSOF). The quantity of alpha-tocopherol naturally present in COCs diminished by half during IVM (p < 0.05), although in the presence of ascorbic acid it remained constant. A greater amount of alpha-tocopherol was detected in COCs matured in medium supplemented with this antioxidant (p < 0.05), but the addition of alpha-tocopherol plus ascorbic acid maintained higher levels of alpha-tocopherol (p < 0.05). Significant differences were not observed in the percentages of nuclear maturation and fertilization among different treatments. The presence of alpha-tocopherol or ascorbic acid in the maturation medium failed to modify the percentage of blastocysts obtained, unlike the addition of both antioxidants when a significant decrease was observed (p < 0.05). Absorbic acid maintained the antioxidant capacity of the alpha-tocopherol incorporated to COC membranes during IVM. The active form of vitamin E during maturation impaired the acquisition of oocyte developmental competence.     

Effects of Polychlorinated Biphenyls 28, 30 and 118 on Bovine Spermatozoa In Vitro

Decline of semen quality due to endocrine‐disrupting chemicals is of concern globally. Among endocrine disrupting chemicals (EDC), Polychlorinated biphenyls (PCB) are associated with reduced semen quality in various epidemiological studies. In this study, we evaluated the direct effects of selected PCBs (28, 30 and 118) on fresh spermatozoa of Simmetial bulls aged 2–4 years were evaluated in vitro by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay and computer assisted semen analysis (CASA) (SCA; Microptics) analysis. IC50 values were found as 8.45, 5.45 and 9.55 ng/ml for PCB 28, 30 and 118, respectively. Total motility, progressive motility and viability decreased dependent on dose and duration of exposure (0, 2, 4 h). Total motility at IC50 doses decreased the most in PCB 28 (72.24%) followed by 30 (60.75%) and 118 (64.77%) at 2nd hour following exposure. Motility results were found to be in accordance with the vitality and morphology data where total abnormalities (especially reacted acrosome rate) were found to have increased.