Exposure to L-Ascorbic Acid or α-Tocopherol Facilitates the Development of Porcine Denuded Oocytes from Metaphase I to Metaphase II and Prevents Cumulus Cells from Fragmentation

It is known that alpha-tocopherol (vitamin E) and L-ascorbic acid (vitamin C) can modulate many biochemical processes intracellularly or extracellularly as antioxidants. The objective of the present study was to investigate the effects of alpha-tocopherol and L-ascorbic acid on porcine oocyte meiotic maturation, viability and the functions of cumulus cells. In two independent experiments, porcine oocytes with or free from cumulus cells were exposed to different levels of alpha-tocopherol (0, 10, 100 and 200 microM) or L-ascorbic acid (0, 50, 250 and 750 microM). Cumulus expansion, cumulus cell DNA fragmentation, meiotic maturation and degeneration of oocytes were assessed 48 h after in vitro culture. The results showed that: (1) neither alpha-tocopherol nor L-ascorbic acid influenced cumulus expansion but both prevented cumulus cell DNA fragmentation. (2) Alpha-tocopherol lowered the percentage of denuded oocytes (DOs) arrested at germinal vesicle stage (GV). Among the oocytes undergoing germinal vesicle breakdown (GVBD) proportion, fewer DOs treated by alpha-tocopherol were at metaphase I (MI) and more at metaphase II (MII). L-ascorbic acid caused lower percentage of DOs arrested at GV stage and higher percentage of DOs undergoing GVBD, especially at MII. The influences of alpha-tocopherol and L-ascorbic acid were not obvious in cumulus-enclosed oocytes (CEOs). (3) Both vitamins compromised the viability of CEOs and DOs. These results indicate that exposure to alpha-tocopherol or L-ascorbic acid promotes the development of porcine DOs from MI to MII and prevents cumulus cell DNA fragmentation at certain levels, especially 10 microM alpha-tocopherol or 250 microM L-ascorbic acid.     

Effect of α-Tocopherol on Bovine In Vitro Fertilization

The objectives of this work are to determine if exogenous supplementation with α-tocopherol increases the in vitro fertilization (IVF) rate of bovine oocytes and improves viability of selected spermatozoa after 'swim-up'. The percentage of fertilized oocytes was significantly but negatively correlated ( r  = −0.941, p < 0.01) with the concentration of α-tocopherol. The control resulted in 95% of fertilized oocytes, which decreased as follows: 25 μM α-tocopherol (α25) 86%, 50 μM α-tocopherol (α50) 74%, 100 μM α-tocopherol (α100) 66% and 200 μM α-tocopherol (α200) 56%. Relatively to sperm viability after 'swim-up' with α-tocopherol supplementation, this antioxidant proved to have a beneficial effect as its concentration increased up to α50, decreasing for the concentrations of α100 and α200. Control resulted in 83% of live cells and 16% of dead cells; α25 resulted in 88% of live cells and 12% of dead cells; α50 resulted in 91% of live cells and 9% of dead cells; α100 resulted in 67% of live cells and 33% of dead cells; and finally α200 resulted in 57% of live cells and 42% of dead cells. In summary, the present study allows to conclude that, in our conditions, supplementation with the antioxidant α-tocopherol in IVF of bovine oocytes has a detrimental effect on fertilization rates. Nevertheless, exogenous supplementation with α-tocopherol at a concentration of 50 mM in the sperm-TALP media during the 'swim-up' technique has a significant beneficial effect on the selected spermatozoa viability.     

培养介质、卵丘细胞和卵泡直径对猪卵母细胞体外成熟的影响

A类卵母细胞在mTCM 199、NCSU2 3和NCSU37体系中培养 4 4～ 5 2小时后 ,成熟率分别为 76 .1%、78.1%和 6 5 .2 %。前两者差异不显著 (P >0 .0 5 ) ,但显著高于后者 (P <0 .0 5 )。卵母细胞在添加eCG和hCG的NCSU2 3体系中的成熟率 (75 .6 % )明显高于添加FSH的LH和成熟率 (6 5 .2 % ) (P <0 .0 5 )。A、B、C三类卵母细胞在NCSU2 3的成熟率分别为 73.3%、6 0 .4 %和 11.0 % ,三者间差异显著 (P <0 .0 5 )。大 (ф >6mm)、中 (ф =3～ 6mm)和小 (ф <3mm)三种卵泡中的卵母细胞在NCSU2 3中培养后 ,成熟率分别为 5 6 .2 % ,78.1%和 5 1.9% ,中等卵泡中卵母胞的体外成熟率显著高于其他两组 (P <0 .0 5 )。     

Role of Cumulus Cells on In Vitro Maturation of Canine Oocytes

The objectives of the present study were to investigate the relationship between the morphological status of cumulus cells surrounding canine oocytes after maturation culture and the meiotic stage of the oocytes. In addition, the effect of the removal of cumulus cells from canine cumulus-oocyte complexes (COCs) during maturation culture on their meiotic competence was examined. Canine COCs were collected from bitches at the anoestrous and dioestrous stages and only COCs with >110 microm in vitelline diameter were cultured in medium 199 with 10% canine serum for 72 h. In the first experiment, the relation between the morphological status of cumulus cells surrounding oocytes cultured for 72 h and their meiotic stages was examined. At the end of maturation culture, the proportions of intact, partially nude and completely nude oocytes were 65.2%, 22.9% and 11.9%, respectively. The proportion of maturation to metaphase II of completely nude oocytes was highest among the oocytes with different morphological status of cumulus cells. In the second experiment, the cumulus cells were partially or completely removed from COCs at 48 h after the start of maturation culture and the oocytes were cultured for a further 24 h. The proportion of oocytes reaching metaphase II in the completely denuded oocytes was significantly higher than that in the control oocytes without the removal treatment of cumulus cells. The results indicate that morphological status of cumulus cells surrounding oocytes may be related to the nuclear maturation of canine oocytes, and the removal of cumulus cells from COCs during maturation culture can promote the completion of oocyte meiotic maturation.     

卵丘细胞对卵母细胞成熟、受精和胚胎发育的影响试验

将从猪卵巢上获取的卵母细胞根据卵丘细胞层数的多少分为两类,并将这两类卵母细胞进行成熟培养、体外受精和孤雌激活,以验证两类卵母细胞的发育潜能.结果显示,将两类卵母细胞分别进行成熟培养时,优级卵的成熟率高于次级卵（67.42±177;1.52％vs 48.33±177;2.85％）,且差异极显著（P＜0.01）;将成熟的卵母细胞进行孤雌激活后,优级卵的囊胚率高于次级卵（58.00±177;2.88％ vs 41.00±177;6.40％）,且差异极显著（P＜0.01）,但囊胚总细胞教两者无显著差异（P＞0.05）;将成熟的卵母细胞进行体外受精后,优级卵的囊胚率、囊胚总细胞数均高于次级卵（18.00土5.70％ vs 4.25±177;2.31％,41.7±177;3.33 vs 36.2土2.10）,且差异极显著（P＜0.01）;进行受精卵孵育时,未去除卵丘细胞的胚胎卵裂率、囊胚率、囊胚总细胞数均高于去除卵丘细胞的（88.14土7.48％ vs 58.69±177;2.89％,51.2±177;7.33％ vs 11.92±177;2.29％,41.7±177;3.33 vs 36.8±177;3.15）,且差异极显著（P＜0.01）.以上结果说明：卵丘细胞层数较多的卵母细胞成熟率高,且其孤雌和体外受精胚胎的发育潜能也好;卵丘细胞存在时,有助于卵母细胞的受精及以后的胚胎发育.     

半胱氨酸对猪卵母细胞体外成熟、体外受精及GSH水平的影响

体外受精技术也称胚胎生产技术（invitro production,IVP）,包括卵母细胞的体外成熟、精子的获能、卵子的体外受精和受精卵的体外培养等几个连续的过程。半胱氨酸是GSH的前体物质,在牛体外胚胎生产过程中疏基复合物能增加细胞内GSH的合成,在受精和胚胎的开始阶段保持高浓度GSH可以增加发育率。试验的目的是评价半胱氨酸对猪卵母细胞的成熟率、受精率及成熟培养时期卵母细胞内GSH水平的影响,现报道如下。     

Effects of Co‐culture of Cumulus Oocyte Complexes with Denuded Oocytes During In Vitro Maturation on the Developmental Competence of Cloned Bovine Embryos

This study evaluated the effects of co‐culture of immature cumulus oocyte complexes (COCs) with denuded immature oocytes (DO) during in vitro maturation on the developmental competence and quality of cloned bovine embryos. We demonstrated that developmental competence, judged by the blastocyst formation rate, was significantly higher in the co‐cultured somatic cell nuclear transfer (SCNT+DO, 37.1 ± 1.1%) group than that in the non‐co‐cultured somatic cell nuclear transfer (SCNT‐DO, 25.1 ± 0.9%) group and was very similar to that in the control IVF (IVF, 38.8 ± 2.8%) group. Moreover, the total cell number per blastocyst in the SCNT+DO group (101.7 ± 6.2) was higher than that in the SCNT‐DO group (81.7 ± 4.3), while still less than that in the IVF group (133.3 ± 6.0). Furthermore, our data showed that mRNA levels of the methylation‐related genes DNMT1 and DNMT3a in the SCNT+DO group were similar to that in the IVF group, while they were significantly higher in the SCNT‐DO group. Similarly, while the mRNA levels of the deacetylation‐related genes HDAC2 and HDAC3 were significantly higher in the SCNT‐DO group, they were comparable between the IVF and SCNT+DO groups. However, the mRNA levels of HDAC1 and DNMT3B were significantly higher in the SCNT+DO group than in the other groups. In conclusion, the present study demonstrated that co‐culture of COCs with DO improves the in vitro developmental competence and quality of cloned embryos, as evidenced by increased total cell number.     

Effect of the Removal of Cumulus Cells on the Nuclear Maturation, Fertilization and Development of Porcine Oocytes

The present study was conducted to investigate the effects of attachment of cumulus cells to porcine oocytes during the process of maturation and fertilization on the nuclear maturation, fertilization and subsequent development after in vitro fertilization (IVF). In the first experiment, the cumulus cells were removed from cumulus-oocyte complexes (COCs) at 0, 24 and 42 h after the onset of maturation culture and were then cultured until reaching 42 h of cultivation. In the second experiment, COCs were denuded as described in the first experiment, then fertilized and cultured for 7 days. As a control, cumulus cells were allowed to maintain attachment to the oocytes until the end of IVF. The proportion of oocytes reaching metaphase II significantly increased with the delay in the removal treatment of cumulus cells. The proportion of normal fertilization gradually increased with delay in the removal treatment of cumulus cells from COCs until the end of IVF. However, no significant difference in the proportion of normal fertilization was found between the 42-h and control groups. The removal treatment of cumulus cells in the 0- and 24-h group significantly (p < 0.05) decreased the proportion of cleaved embryos when compared with the control, and none of them developed to the blastocyst stage. The proportion of development to the blastocyst stage was significantly higher (p < 0.05) in the control group than in the 42-h group (18.1% vs 12.4%; p < 0.05). The present study indicates that the attachment of cumulus cells to the oocyte during maturation and fertilization is important to support oocyte nuclear maturation, fertilization and subsequent embryo development. Particularly, the attachment of cumulus cells to the oocyte during IVF promotes embryonic development.     

Effect of Lycopene on Cytoplasmic Maturation of Porcine Oocytes In Vitro

The aim of the present study was to improve cytoplasmic maturation of porcine oocytes by the addition of lycopene into in vitro maturation (IVM) media. We designed six experimental groups; IVM medium was supplemented with 10 IU/ml FSH, FSH and 10 IU/ml human chorionic gonadotrophin (hCG), or FSH and 7 μm lycopene in the first half of the IVM culture (0–22 h) followed by further culture (22–44 h) with or without hCG. The addition of lycopene into IVM media delayed the interruption of communication between an oocyte and the cumulus cells. Although meiotic competence was similar among the six groups, the glutathione level of matured oocytes was significantly higher in the lycopene‐supplemented group (9.89 pmol per oocyte) than that in other groups (7.25 and 7.81 pmol per oocyte). Fertilization rate was significantly improved in lycopene‐supplemented groups (58.3%) more than that in the group supplemented with FSH only (43.1%), whereas there were no differences in developmental competence among the groups (blastocyst rate: 20.1–29.5%). These results indicate that insufficient cytoplasmic maturation during conventional IVM resulted by disconnection of the gap junction between an oocyte and the cumulus cells in the early phase during IVM culture. We concluded that lycopene induced a prolonged sustainment of gap junctional communication between an oocyte and the cumulus cells during porcine IVM culture, which was an effective cytoplasmic maturation of porcine IVM oocytes.     

卵丘细胞与卵母细胞解离对小鼠卵子体外成熟及受精的影响

卵丘细胞与卵母细胞的解离会降低小鼠卵母细胞的成熟质量,该研究将解离所得裸卵用不同种成分明确的成熟培养液进行体外成熟、体外受精、体外发育,从而确定卵丘细胞与卵母细胞的解离对小鼠卵母细胞成熟、受精、发育的影响,并通过筛选建立起最优的试验体系,为去除卵丘细胞的卵母细胞体外成熟质量的提高及后续研究提供参考依据。结果显示,裸卵的成熟率与成熟培养液的选择密切相关,TYH组、HTF组极显著优于M199组、α-MEM组;卵丘细胞与卵母细胞的解离与否对受精率的影响是巨大的,解离后(10%～28%)与解离前(48%～76%)差异极为显著(P<0.01);卵丘细胞与卵母细胞的解离与否对发育率的影响未发现显著差别(P>0.05)。因此,卵丘细胞与卵母细胞的解离主要影响了小鼠卵母细胞的体外受精率,通过选用适当的培养液可以相对改善该情况。     

In Vitro Fertilization and Development of Porcine Oocytes Matured in Follicular Fluid

This study was conducted to assess the fertilization and development of porcine oocytes matured in a solo follicular fluid (pFF) using different in vitro culture systems and insemination periods. Cumulus-oocyte complexes (COCs), follicular cells (FCs), and pFF were collected from the follicles of ovaries. The pFF was used as a maturation medium (MpFF) after supplementation with follicle stimulating hormone (FSH) and antibiotics. The COCs were matured in a 15 ml test tube containing 3.5 ml of MpFF with FCs (5.2 × 10⁶ cells/ml; rotating culture system) or 2 ml of MpFF without FCs in a 35-mm petri dish (static culture system) for 44 to 48 h. After maturation culture, oocytes were co-incubated with frozen-thawed spermatozoa for 5 h and then cultured for 7 days. The total mean rates of sperm penetration, normal fertilization, male pronucleus (MPN) formation, cleavage, and development to the blastocyst stage of oocytes after insemination were significantly higher (P<0.01) in the rotating culture system than in the static culture system. In conclusion, compared with the static culture system, the rotating culture system is adequate for the production of developmentally competent porcine oocytes when MpFF is used as a maturation medium.     

共培养系统的体细胞类型和状态对猪胚胎早期发育的影响

经体外成熟、受精和培养获得猪胚胎 ,采用体细胞共培养研究了体细胞类型和状态对胚胎早期发育的影响。取体外成熟的不同直径卵泡 (>5 m m,2～ 5 mm)卵母细胞的卵丘团 (颗粒细胞团 ) ,培养铺层后与猪受精卵共培养 ,组间受精卵的卵裂率和发育能力无显著差异 ;根据卵巢的状况对猪输卵管上皮细胞 (POECs)的状态进行分组 ,受精卵和卵巢表面布满卵泡的 POECs共培养 ,卵裂率显著低于卵巢表面有黄体和 /或红体的 POECs共培养组 (P<0 .0 5 ) ,虽然各组间 3～ 4-细胞的发育率无显著差异 ,但卵巢表面有红体和卵泡的 POECs共培养组的 >4-细胞的发育率显著高于卵巢表面布满卵泡的 POECs共培养组 (P<0 .0 5 ) ;受精卵在共培养系统和非共培养系统中的卵裂率无显著差异 ,受精卵非共培养系统中 3～ 4-细胞的发育能力显著低于颗粒细胞共培养组 (P<0 .0 5 ) ,极显著低于 POECs共培养组 (P<0 .0 1) ,无能力突破 4-细胞继续发育 ,与颗粒细胞单层、POECs单层共培养的受精卵 >4-细胞的发育率分别为 2 4.0 %、5 3.8% ,差异显著 (P<0 .0 5 )。结果表明 ,共培养系统对胚胎体外发育的作用 ,一方面与体细胞类型有关 ,另一方面也受输卵管上皮细胞状态的影响     

Effect of Follicle Size on In Vitro Maturation of Pre‐Pubertal Porcine Cumulus Oocyte Complexes

Very small follicles (<3.0 mm diameter) are over‐represented on the surface of ovaries of non‐cycling pigs, and the oocytes collected from these follicles generally have reduced developmental competence in vitro. This study examined the effect of follicle size on the nuclear maturation (n = 608), the potential of parthenogenetic activation (n = 243) and the cyclic AMP (cAMP) content of pre‐pubertal porcine oocytes (n = 480). In addition, the influence of follicle size on steroid hormone synthesis was analysed. Cumulus oocyte complexes (COCs) flushed from small (2.5–4.0 mm) or large (4.5–6.0 mm) ovarian follicles were cultured for 0, 28 and 46 h. After 46 h of IVM, a greater proportion of oocytes from 4.5‐ to 6.0‐mm follicles reach metaphase II (MII) compared with those from follicles with 2.5–4.0 mm of diameter (96.1 vs 77.0%, respectively; p < 0.001). Parthenogenetic activation of oocytes from large follicles produced higher developmental rates than oocytes from large follicles (p < 0.05). At 28 h, the IVM medium with oocytes from large follicles contained significantly more 17ß‐oestradiol (E₂) than the medium with oocytes from small follicles (5.55 vs 3.45 ng/ml, respectively; p < 0.05) and at 46 h, the medium with oocytes from small follicles contained significantly more progesterone (P₄) than the medium with oocytes from large follicles (276.7 vs 108.2 ng/ml, respectively, p < 0.05). Porcine oocytes from large follicles have higher nuclear and cytoplasmic maturation capacities, but the differences did not appear to be cAMP‐mediated. Our findings also suggest that COCs from small follicles undergo more intensive luteinization than COCs from large follicles. The results show that oocytes from follicles with a diameter greater than 4.0 mm are more suitable for in vitro studies.     

体外培养时间,卵丘细胞数目对卵母细胞膜电位的影响

应用细胞内微电极技术,研究体外培养时间、卵丘细胞数目对猪卵母细胞模电位的影响。结果表明：体外培养时间对卵母细胞膜电位有显著影响。体外培养０ｈ膜电位为－８．９７±０．５０ｍＶ,１８ｈ膜电位为－４６．４０±１．７０ｍＶ,２４ｈ膜电位为＋１０．６０±１．００ｍＶ,３６ｈ膜电位为＋２６．５０±１．００ｍＶ,５０ｈ膜电位为＋２６．４０±１．１０ｍＶ。卵丘细胞数目对卵母细胞膜电位亦有影响。多丘卵的膜电位为－８．９７±０．５０ｍＶ,少丘卵膜电位为－１．５５±０．６５０ｍＶ,无丘卵的膜电位为＋２．４０±０．３０ｍＶ。     

促卵泡素与促黄体素对猪卵母细胞体外成熟的影响

本试验探讨了促性腺激素（FSH、LH）对猪卵母细胞体外成熟的影响,最终找到了其合理的使用剂量。在成熟液中添加LH浓度分别为1、5、10IU／mL时,与没有添加FSH与LH的对照组（15．9％）相比,成熟率有显著提高,成熟率分别为49．1％、30．0％、36．3％。LH浓度为1IU,mL的实验组成熟率最高,显著高于对照组（P〈0．05）;然后以成熟液中只添加1IU/mLLH为对照组,试验组分别添加1、5、10IU/mLPSH。试验结果表明：添加FSH浓度为5和10IU/ml时其成熟率分别为40．1％、27．6％,低于对照组（49．0％）。添加FSH浓度为1IU／mL时其成熟率（49．1％）高于对照组（49．0％）,但差异不显著（P〉0．05）。两组试验同时得出,随着LH与FSH添加浓度的增加,成熟率呈下降趋势。通过本试验结果得出,在体外成熟培养猪卵母细胞时,各添加1IU／mL LH与FSH时,得到最佳的成熟效果。     

Effect of Porcine and Ovine FSH on Nuclear Maturation of Pig Oocytes In Vitro

The effect of porcine or ovine FSH on the maturation rate of porcine oocytes and on the time course of meiotic progression was studied. Groups of 20 grade‐A cumulus oocyte complexes, aspirated from slaughterhouse cycling‐gilt ovaries, were cultured in vitro in 400 μl of Modified Parker's Medium supplemented with oestrous cow serum and porcine FSH (Folltropin®‐V, 0.50 mg/ml) or ovine FSH (Ovagen^TM, 0.44 iu/ml), in four‐well dishes under mineral oil, at 38.5°C, 5% CO₂ in humidified air. At the end of each 3‐h interval, from 3 to 42 h of culture, the nuclear status of oocytes was assessed microscopically (1000×), after fixation (methanol/acetic acid: 3/1) and orcein (2%) staining. Oocytes were classified as (i) immature (IMM), i.e. oocytes at germinal vesicle stage, germinal vesicle break down and prophase I, (ii) metaphase I (MI) and (iii) metaphase II (MII), i.e. oocytes at anaphase I, telophase I and metaphase II. Data were analysed using regression analysis, chi‐square and t‐test. Nuclear status was assessed in 1610 oocytes (porcine FSH: 787, ovine FSH: 823). Most of the oocytes were at MI from 24 to 33 h (porcine FSH 60.27%, ovine FSH 42.80%, p < 0.001) and at MII from 36 to 42 h (porcine FSH 80.38%, ovine FSH 67.45%, p < 0.01) of culture. Significantly higher maturation rate was observed in porcine FSH than in ovine FSH treated oocytes (86.69 ± 12.97%, 71.34 ± 9.86%, mean ± SD, p < 0.05), after 42 h of culture. In conclusion, under the specific culture conditions, porcine FSH seems to support pig oocyte maturation better than ovine FSH.     

促卵泡素与促黄体素对猪卵母细胞体外成熟的影响

本试验探讨了促性腺激素(FSH、LH)对猪卵母细胞体外成熟的影响,最终找到了其合理的使用剂量。在成熟液中添加LH浓度分别为1、5、10 IU/mL时,与没有添加FSH与LH的对照组(15.9%)相比,成熟率有显著提高,成熟率分别为49.1%、30.0%、36.3%。LH浓度为1 IU/mL的实验组成熟率最高,显著高于对照组(p<0.05);然后以成熟液中只添加1 IU/mLLH为对照组,试验组分别添加1、5、10 IU/mLFSH。试验结果表明:添加FSH浓度为5和10 IU/ml时其成熟率分别为40.1%、27.6%,低于对照组(49.0%)。添加FSH浓度为1 IU/mL时其成熟率(49.1%)高于对照组(49.0%),但差异不显著(p>0.05)。两组试验同时得出,随着LH与FSH添加浓度的增加,成熟率呈下降趋势。通过本试验结果得出,在体外成熟培养猪卵母细胞时,各添加1 IU/mL LH与FSH时,得到最佳的成熟效果。     

微囊藻毒素-LR对猪体外成熟卵母细胞氧化损伤与凋亡的影响

旨在探讨微囊藻毒素-LR(microcystin-LR,MC-LR)对体外成熟猪卵母细胞的毒性损伤及其潜在损伤机制.本研究从屠宰场所获得的猪卵巢中收集GV期卵母细胞,将其随机分为4组,在卵母细胞体外成熟培养液中分别添加0、20、40和60μg? mL-1 MC-LR,研究MC-LR对卵母细胞第一极体(Pbl)排出、纺锤...     

透明质酸对牛卵母细胞体外成熟影响的研究

在改良的基础培养液中添加HA,主要探讨HA对牛卵母细胞成熟的影响。结果表明,当mTCM-199中HA浓度为3．0mg／mL时,第一极体排出率和卵裂率显著高于其他各组（P〈0．05）,初步表明3．0mg／mL是无血清培养中HA的最佳浓度。当在mTC-199中添加HA、BSA和OCS时,OCS组的第一极体排出率显著高于其他两组（P〈0．05）,分别为83．40％、84．33％和92．17％,但HA组与BSA差异不显著（P〉0．05）;卵裂率三者差异均不显著（P〉0．05）;表明在无血清培养中HA可代替BSA,但是培养的效果不如血清。HA在mTCM-199和mSOF基础培养基中,对卵母细胞的第一极体排出率和卵裂率无明显差异（P〉0．05）。表明在无血清培养下,HA在复杂和简单的培养液中都支持卵母细胞的成熟。