成熟时间对水牛卵母细胞体外成熟的影响研究

研究体外成熟时间对沼泽型水牛卵母细胞核质成熟的影响。试验对比了24 h、25h、26 h2、7 h的成熟时间对卵母细胞第一极体排出率及体外受精后卵裂的影响。结果表明,在至少24 h之内大部分水牛卵母细胞就已经完成了完全的核质成熟。     

水牛卵母细胞体外成熟及体外受精过程中的皮质颗粒变化

用异硫氰荧光素联接的小扁豆凝集素(Fluorescein isothiocyanate-labelled Lens culinaris,FITC-LCA)标记不同体外成熟时间和不同体外受精时间的水牛卵母细胞的皮质颗粒,用激光共聚焦显微镜检测其分布情况.结果发现,皮质颗粒在水牛卵母细胞体外成熟培养前,70.1%卵母细胞的皮质颗粒呈现中间分布;培养24 h后,皮质颗粒皮层分布的卵母细胞达59.8%,分布形式由完全聚合向完全分散逐步转变.对不同体外成熟时间的卵母细胞进行体外受精时发现,体外成熟12 h的卵母细胞仅在受精后3 h有12.9%的皮质颗粒外排.随着成熟时间的增加,皮质颗粒的排放也趋于明显,成熟24 h的卵母细胞受精后3 h皮质颗粒外排率可达100%.结果表明,在水牛卵母细胞的成熟过程中,皮质颗粒的分布由中间分布逐渐向皮层分布转变,最后在卵母细胞的质膜下排列成单层;体外受精过程中卵母细胞皮质颗粒的排放速度取决于其在卵母细胞中的分布情况,故而与体外成熟时间呈正相关.     

不同成熟时间水牛卵母细胞成熟与凋亡的比较

为了解卵母细胞体外成熟与凋亡过程,进而提高卵母细胞体外成熟率,本试验研究了不同成熟时间水牛卵母细胞体外核、质成熟与凋亡的情况。结果表明:培养24 h,卵母细胞核、质成熟率分别达到61.4%和59.8%,与其他各时间组对比差异显著(P0.05),凋亡率也呈增加趋势,但差异不显著(P0.05)。     

磷酸二酯酶抑制剂对水牛卵母细胞体外成熟的影响

本研究探讨了磷酸二酯酶(PDE)抑制剂Milrinone对水牛卵母细胞成熟的影响。水牛卵母细胞在含50μmol/L Milrinone的成熟液中培养16 h后,在不含Milrinone的成熟液中培养12 h、16 h和20 h,挑选形态正常的卵母细胞受精后培养,其分裂率(分别为59.1%,48.5%和50.6%)显著高于再培养8 h(29.5%)的卵母细胞(P0.05),但与其对照组(66.2%)相近,同时其卵母细胞受精后的囊胚发育率(分别为36.9%,33.6%和23.9%)亦显著高于8 h(15.5%)的卵母细胞(P0.05),但均与正常成熟培养的对照组(33.4%)相近。结果表明Milri-none对水牛卵母细胞的成熟具有明显的可逆抑制作用,经成熟抑制后的水牛卵母细胞恢复成熟后仍可保持较高的发育潜能。     

磷酸二酯酶抑制剂对水牛卵母细胞减数分裂成熟的影响

本研究探讨了磷酸二酯酶抑制剂米力农(milrinone)对水牛卵母细胞体外自发成熟和促性腺激素诱导成熟的影响,以便提高卵母细胞体外成熟质量。试验对水牛卵丘卵母细胞复合体(COCs)培养不同时间或采取不同处理后,取出卵母细胞剥光后固定,然后用间苯二酚蓝染色,观察卵母细胞核成熟情况。结果表明:(1)Milrinone对水牛COCs的自发成熟具有抑制作用,且具有剂量依赖关系;(2)Milrinone对水牛卵母细胞体外自发成熟的抑制作用随培养时间的延长没有减弱,可作为水牛卵母细胞成熟过程中的核成熟抑制剂;(3)Milrinone能显著抑制促卵泡激素(FSH)诱导的水牛COCs体外成熟,但是随着时间的延长,这种抑制作用可以部分被FSH克服。     

水牛卵母细胞孤雌激活及孤雌胚与体外受精胚发育比较

对MII期水牛卵母细胞进行人工诱导激活可帮助人们间接判断体外成熟卵母细胞质量的优劣,且卵母细胞的充分激活也是提高核移植效率的关键因素之一。本试验比较了水牛卵母细胞体外成熟时间对孤雌激活胚发育能力的影响及不同化学激活方法对水牛卵母细胞孤雌激活效果的影响,并在相同条件下,对孤雌激活胚与体外受精胚的发育能力进行了比较。结果表明,水牛卵母细胞体外成熟27h或30h的囊胚发育率（19.0%or 17.7%）明显高于体外成熟21h或24h的囊胚发育率（12.3%or 13.8%）;Ion联合6-DMAP激活水牛卵母细胞的效果优于其他激活方法;在相同条件下,孤雌激活胚的囊胚发育率显著高于体外受精胚（13.0%vs.21.7%）。     

牛卵巢卵母细胞体外培养成熟条件的建立

研究不同犊牛血清浓度、培养时间和不同类型血清对牛卵母细胞体外成熟的影响。结果表明,添加体积分数为10%,15%和20%的FBS时,各组间卵母细胞成熟率差异不显著(p>0.05);培养时间为16h时卵母细胞成熟率与培养时间为20h和24h时的差异极显著(p<0.01),而培养时间为20h和24h时卵母细胞成熟率差异不显著(p>0.05);培养基添加OCS对卵母细胞成熟的影响效果与添加FBS的无显著差异(p>0.05),二者的卵母细胞的核成熟率均达到80%以上。     

水牛卵母细胞孤雌激活及孤雌胚与体外受精胚发育比较

比较了水牛卵母细胞体外成熟时间对孤雌激活胚发育能力的影响,以及不同化学激活方法对水牛卵母细胞孤雌激活效果的影响,并在相同条件下,对孤雌激活胚与体外受精胚的发育能力进行了比较.结果表明,水牛卵母细胞体外成熟27 h或30 h的囊胚发育率(19.0%、17.7%)明显高于体外成熟21 h或24h的囊胚发育率(12.3%、13.8%);Ion联合6-DMAP激活水牛卵母细胞的效果优于其他几组激活方法;在相同条件下,孤雌激活胚与体外受精胚的发育能力存在着差异,其中卵裂率差异不显著,但孤雌激活胚的囊胚发育率显著高于体外受精胚.     

水牛卵母细胞成熟过程中激活蛋白激酶C对受精后原核形成的影响

为了研究成熟过程中激活蛋白激酶C(PKC)对水牛卵母细胞受精后原核形成的影响,试验采用水牛卵丘-卵母细胞复合体在不同成熟培养液(即添加PVA、FCS、PMA和PVA的基础成熟液或添加4α-PDD和PVA的基础成熟液)中成熟24 h后,将水牛卵母细胞随机分为5组进行体外受精。结果表明:20小时时检查原核的形成,PMA成熟培养处理的卵母细胞受精后的原核形成率为(66.7±2.3)%,与PVA和FCS阴性对照组[分别为(51.4±3.6)%、(46.8±5.1)%]相比差异不显著(P0.05),但激活PKC后受精形成原核的卵母细胞数比添加4α-PDD的对照组高且差异显著(P0.05)。说明在水牛卵母细胞成熟过程中激活PKC有利于提高两原核的形成率。     

水牛卵泡颗粒细胞对卵母细胞体外成熟的影响

为了系统研究颗粒细胞对水牛卵母细胞体外成熟的影响,使用颗粒细胞条件液处理或单层颗粒细胞和卵母细胞共培养的方法,探讨颗粒细胞共培养对水牛卵母细胞体外成熟和早期胚胎发育的影响.结果显示,添加颗粒细胞传代接种第2天收集的20％颗粒细胞条件液到水牛卵母细胞成熟液中能显著提高水牛卵母细胞体外成熟率和囊胚发育率(P＜0.05);然...     

In Vitro Maturation and Fertilization of Buffalo Oocytes: Effects of Storage of Ovaries, IVM Temperatures, Storage of Processed Sperm and Fertilization Media

Studies were conducted to examine the possibility of preserving slaughterhouse‐derived buffalo ovaries at 4°C for 0 (control), 12 and 24 h to maintain the developmental competence of the oocytes (experiment 1), to assess the effect of incubation temperature during oocyte maturation on rates of in vitro maturation (IVM) and in vitro fertilization (IVF) of buffalo oocytes and embryo development (experiment 2), and to examine the effect of storage at 25°C for 0 (control), 4 and 8 h of frozen–thawed buffalo sperm and BO and H‐TALP as sperm processing and fertilization media on cleavage and embryo development in vitro of buffalo oocytes (experiment 3) in order to optimize the IVF technology in buffalo. Results suggested that storage of ovaries at 4°C for 12 or 24 h significantly (p < 0.05) reduced the developmental potential of oocytes. Incubation temperatures during the IVM influenced the fertilization rate but had no significant effect on maturation and subsequent embryo development. The incubation temperature of 38.5°C during IVM was found to be optimum for embryo production in vitro. Storage of frozen–thawed sperm at 25°C for 8 h significantly (p < 0.05) decreased its ability to cleave the oocytes. Sperm processed in BO medium had significantly (p < 0.05) higher ability to cleave the oocytes than the H‐TALP medium.     

Theca cell-conditioned medium added to in vitro maturation enhances embryo developmental competence of buffalo (Bubalus bubalis) oocytes after parthenogenic activation

Theca cells (TCs) play a key role in follicular growth and atresia. TCs synthesize androgens that act as substrate for granulosa cells (GCs) aromatization to estrogens needed for oocyte maturation. However, the effects of TCs in the form of conditioned medium on in vitro maturation (IVM) and developmental competence of buffalo oocytes remain unclear. In the present study, we examined the impacts of TC-conditioned medium (TCCM) on maturation efficiency and embryo development of buffalo oocytes after parthenogenic activation (PA). Our results showed that TCCM that was collected on day 2 and added to IVM medium at a 20% proportional level (2 days & 20%) exerted no significant effect on IVM rate (43.06% vs. 44.71%), but significantly (p  < .05) enhanced embryo development (oocyte cleavage, 80.93% vs. 69.66%; blastocyst formation, 39.85% vs. 32.84%) of buffalo oocytes after PA compared with the control group. However, monolayer TC significantly (p < .05) promoted both maturation efficiency (48.84% vs. 44.53%) and embryo development (oocyte cleavage, 80.39% vs. 69.32%; blastocyst formation, 35.38% vs. 29.25%) of buffalo oocytes after PA compared to that in the control group. Furthermore, TCs secreted some testosterone into the conditioned medium, which significantly (p < .05) promoted the expression levels of oestrogen synthesis-related genes (CYP11A1, CYP19A1 and 17β-HSD) in buffalo cumulus–oocyte complexes (COCs). Our study indicated that TCCM (2 days & 20%) did not significantly affect IVM efficiency, but enhanced embryo developmental competence of oocytes after PA principally by stimulating the secretion of testosterone and facilitating estradiol synthesis of buffalo COCs.     

不同促性腺激素添加方式对猪卵母细胞生发泡染色质构型和卵母细胞成熟能力的影响

在卵母细胞体外成熟培养过程中,培养基中添加激素与否及其激素添加的先后顺序是影响猪卵母细胞核成熟和质成熟的一个重要因素.本试验将猪卵母细胞分别在FSH→不含激素、FSH→LH、FSH LH不含激素中培养48 h(培养第20～22 h后换液),并于成熟培养的第24 h(未换液)、48 h将卵母细胞进行荧光染色,观察其生发泡内染色质构型及卵母细胞核成熟情况.实验表明:(1)在IVM的前24 h,添加FSH LH组的GVIV期卵母细胞比例低于只添加FSH组,但差异不显著(8.99%比17.19%,P＞0.05);(2)在FSH存在的情况下,IVM的前期和后期添加LH能促进卵母细胞发生GVBD;(3)FSH LH培养24 h后转入不含激素培养基组,卵母细胞的核成熟比率显著高于添加FSH组和先添加FSH培养24 h后转入添加LH组(P＜0.05).     

Maturation competence of swamp buffalo oocytes obtained by ovum pick-up and from slaughterhouse ovaries

This study was designed with the final goal of improving in vitro embryo production in the Thai swamp buffalo (Bubalus bubalis carabensis). Oocytes were collected by ovum pick-up (OPU) from six non-lactating multiparous swamp buffalo twice per week for 10 consecutive sessions followed by once-weekly collection for 10 consecutive sessions without hormone stimulation. In addition, oocytes were collected from slaughterhouse ovaries that were classified as follows: ovaries from non-pregnant cows with a visible corpus luteum (NPCL); pregnant cows with a corpus luteum (P); and non-pregnant cows without a corpus luteum (NP). Follicles in each group of ovaries were categorized as small (2-4 mm), medium-sized (5-8 mm) or large follicles (≥ 9 mm). The quality of the oocytes was assessed by their capacity to undergo in vitro maturation. The total number of observed follicles per session (all sizes combined) was larger in the once-weekly OPU group compared with the twice-weekly OPU group. In particular, the numbers of small and large follicles were higher in the once-weekly OPU group (5.2 ± 0.7 and 0.9 ± 0.2, respectively) than in the twice-weekly OPU group (3.9 ± 0.5 and 0.5 ± 0.1). The number of medium-sized follicles did not differ between the groups. The percentages of oocytes with an abnormal spindle morphology were not different between oocytes from the twice-weekly (30.0%) and the once-weekly (28.6%) OPU groups. A higher percentage of oocytes obtained in vitro (49.5%) exhibited nuclear abnormalities compared with those obtained in vivo (≤34.8%) after in vitro maturation. In conclusion, oocytes can be successfully collected by OPU in the swamp buffalo, without hormonal pretreatment, and per week more good-quality oocytes can be collected by twice-weekly OPU. In addition, oocytes collected from slaughterhouse ovaries can be used with the reproductive status of the cow having no influence on the maturation competence of oocytes.     

Aging-related Changes in In Vitro-matured Bovine Oocytes: Oxidative Stress,Mitochondrial Activity and ATP Content After Nuclear Maturation

The objective of this research was to clarify the aging-related changes in in vitro-matured bovine oocytes. Firstly, we examined the fertilization and embryonic development of bovine oocytes after 22 and 30–34 h of in vitro maturation (IVM). The oocytes after 30–34 h of IVM (penetrated by sperm at around 40 h after starting IVM) showed a lower developmental rate to blastocysts (P<0.01), although normal fertilization rates were similar regardless of IVM duration. In the next experiment, reactive oxygen species (ROS), mitochondrial activity and ATP content in oocytes after 20, 30 and 40 h of IVM were examined. The lowest level of ROS was found in the group subjected to 30 h of IVM. The mitochondrial activity and ATP content in the group subjected to 40 h of IVM were higher than in the group subjected to 20 h of IVM (P<0.01), and those in the group subjected to 30 h of IVM showed intermediate values. Thereafter, the mitochondrial activities at 3 days after in vitro fertilization in embryos derived from the oocytes subjected to 22 and 34 h of IVM were evaluated. In the group subjected to 34 h of IVM, high-polarized mitochondria were frequently observed at the periphery of blastomeres. The present results suggest that high mitochondrial activity observed in oocytes after prolonged IVM culture and localization of high-polarized mitochondria at the periphery of blastomeres during early embryonic development may be associated with the low developmental competence in aged bovine oocytes.     

牛有腔卵泡卵母细胞体外成熟的研究

试验从屠宰场收集了 4 8头青年黄牛、34头青年水牛的卵巢共 16 4个 ,共回收可用卵母细胞 86 4枚。水牛平均每个卵巢可回收 3.2 2枚可用卵母细胞 ,相当于黄牛 (6 .72枚 )的一半。试验结果表明 :水牛卵巢生长卵泡少 ,卵母细胞产量少、质量差 ;3种采集黄牛卵泡卵母细胞的方法 ,用抽吸加切割法平均从每个卵巢回收的可用卵数 (7.71枚 )都极显著高于抽吸法 (6 .19枚 )和切割法 (6 .4 4枚 ) (P <0 .0 1) ,但是该法手续繁杂 ,适于一次且只能收集少量卵巢时使用 ;在黄牛和水牛卵母细胞成熟培养液中用 0 .3%PVP代替 10 %FBS ,牛卵母细胞的体外成熟率无显著差异 (P >0 .0 5 )。     

In vitro Development of Buffalo Oocytes in Media-containing Fluids from Different Size Class Follicles

Studies were conducted to investigate the effect of supplementation of fluid from different sized class [small (SFF, < 3 mm), medium (MFF, 3-8 mm) and large (LFF, > 8 mm)] of normal and cystic (CFF) ovarian follicles in oocyte culture media on oocyte maturation rate and embryo development in vitro and to test the efficacy of follicular fluid (FF) from different size classes as a whole oocyte maturation medium. Results suggested that FF were capable of developing buffalo oocytes to embryonic stage in vitro although its efficacy was lower than that of serum. Regardless of high maturation rates after in vitro maturation (IVM) in media containing FF or IVM in whole FF, low blastocyst rates were obtained after in vitro fertilization (IVF) and culture of embryos. Follicular fluid from small follicles had significantly (p < 0.05) higher potential of developing buffalo oocytes to embryonic stage in vitro than that from medium and large follicles. Cystic FF was not capable of supporting development of buffalo oocytes in vitro.     

Effect of Meiotic Stages During <Emphasis Type="Italic">In Vitro</Emphasis> Maturation on the Survival of Vitrified-Warmed Buffalo Oocytes

The present study was conducted to investigate the effect of meiotic stages during in vitro maturation (IVM) on the survival of vitrified-warmed buffalo oocytes, vitrified at different stages of IVM. Cumulus oocyte complexes obtained from slaughterhouse ovaries were randomly divided into 6 groups: control (non-vitrified, matured for 24 h at 38 ± 1^°C, 5% CO₂ in humidified air), and those matured for 0 h (vitrified before IVM) or 6, 12, 18 and 24 h before vitrification. Cumulus oocyte complexes were vitrified in solution consisting of 40% w/v propylene glycol and 0.25 mol/L trehalose in phosphate-buffered saline supplemented with 4% w/v bovine serum albumin. Vitrified cumulus oocyte complexes were stored at −196^∘C (liquid nitrogen) for at least 7 days and then thawed at 37^°C; cryoprotectant was removed with 1 mol/L sucrose solution. Cumulus oocyte complexes in the 0, 6, 12, 18 and 24 h groups were then matured for an additional 24, 18, 12, 6 and 0 h, respectively, to complete 24 h of IVM. Among the five vitrification groups, 89–92% of cumulus oocyte complexes were recovered, after warming, of which 84–91% were morphologically normal. Overall survivability of vitrified cumulus oocyte complexes was lower (p < 0.05) than that of non-vitrified cumulus oocyte complexes (94.5%). Survival rates of cumulus oocyte complexes matured 24 h prior to vitrification (61.3%) were higher (p < 0.05) than those matured for 12 h (46.7%), 6 h (40.6%) and 0 h (37.6%). Nuclear status following 24 h IVM was assessed. A higher proportion of non-vitrified (control) oocytes (72.7%) reached metaphase II (M-II) stage in control than oocytes vitrified for 24 h (60.0%), 18 h (54.4), 12 h (42.3%), 6 h (33.3%) and 0 h (31.6%) (p < 0.05). The results suggest that length of time in maturation medium prior to vitrification influences post-thaw survivability of buffalo oocytes; longer intervals resulted in higher survival rates.     

血清对水牛卵母细胞体外成熟、体外受精及早期胚胎发育的影响

从屠宰场收集了本地水牛55头、黑白花奶牛22头的卵巢共获卵泡847枚,平均每个水牛卵巢回收3.67枚可用卵母细胞,约为黑白花奶牛(10.23枚/头)的1/3。试验分别采用添加与不添加血清的培养液体外成熟培养水牛卵母细胞,结果二者的成熟率无明显毒性差异(58.23%对56.67%),但体外受精后早期胚胎发育的8-细胞率有显著差异(35.4%对23.0%),表明体外成熟液中有无血清对水牛卵母细胞体外成熟率没有影响,但血清对卵母细胞的早期胚胎发育有重要影响。进一步比较成熟液中不添加血清但在受精液及胚胎液中添加血清和在各个阶段均有血清参与的早期胚胎发育率(8-细胞率),表明二者差异不显著(33.8%对35.4%)。经无血清成熟培养液培养的成熟卵母细胞可以经孤雌激活后得到早期胚胎(4细胞)。