EGF基因在动物卵泡发育过程中的研究进展

表皮生长因子(EGF)是表皮上生长家族的重要调节因子之一,可促进细胞增殖分化、调控细胞的衰老以及诱导肿瘤的发生。在动物卵巢卵泡的研究中发现,EGF可以有效地抑制卵泡细胞的凋亡、促进颗粒细胞的增殖和卵母细胞的成熟,因此近年来受到了越来越多的学者的关注。为了进一步认识EGF基因对各级卵泡的调节作用,文章拟从EGF基因的结构、对卵泡发育的作用机理等角度进行阐述,为研究EGF基因参与调控动物卵泡发育过程的作用机制提供参考。     

表皮生长因子促进胚泡植入的研究进展

表皮生长因子在哺乳动物妊娠早期的胚胎发育及胚泡植入中具有重要的生物学功能。表皮生长因子通过旁分泌或（和）自分泌途径,作为胚胎营养因子促进早期胚胎的发育;并且可能通过激活胚泡和调节子宫接受性从而启动胚泡植入。     

IGF在母猪生殖器官中的表达和对早期胚胎发育的作用

胰岛素样生长因子是促合成代谢、促有丝分裂和抗细胞凋亡的因子，能调节脊椎动物细胞的生长、分化和凋亡。研究发现，IGF及其mRNA在妊娠早期母猪的卵巢、输卵管、子宫中都有表达。IGF通过内分泌、自分泌或旁分泌机制在母猪早期胚胎发育、胚胎着床中起着重要的调节作用。     

生长因子在着床前鼠胚发育中的作用

近年来,大量的研究显示。生长因子在哺乳动物着床前胚胎的发育中起了十分重要的作用。首先。哺乳动物着床前胚胎以及生殖道中可以表达多种生长因子及其受体,并且在体外实验中通过添加生长因子,如EGF、IGF-Ⅰ、IGF-Ⅱ等能显著促进胚胎细胞的增生与分化。同时,如果加入抗生长因子抗体或受体抑制剂。可以阻     

不同培养液对牛卵母细胞体外成熟及孤雌胚胎发育的影响

为研究表皮生长因子(EGF)、β-巯基乙醇(β-ME)、亚硫磺酸(HTAU)对牛卵母细胞体外成熟(IVM)及孤雌激活胚胎体外发育(IVC)效果的影响,实验采集牛卵巢采用切割法收集卵丘-卵母细胞复合体(COCs)随机处于不同浓度EGF、β-ME培养液成熟培养24 h后孤雌激活,研究其在不同胚胎培养液中的后续发育,以期筛选出最好的牛卵母细胞IVM-IVC条件。结果表明:添加25、50、100 ng/mL EGF组的成熟率、卵裂率均高于对照组,其中50 ng/mL EGF组的成熟率、卵裂率与对照组差异显著(P<0.05);50、100、500μmol/L的β-ME对牛卵母细胞体外成熟没有促进作用;50 ng/mL EGF与50、100μmol/Lβ-ME组合并无协同作用;胚胎培养基中添加不同浓度EGF对早期胚胎的体外发育无显著影响;而添加100μmol/Lβ-ME组的囊胚率、囊胚细胞数均极显著高于对照组(P<0.01);在成熟液中添加50 ng/mL EGF和100μmol/Lβ-ME、胚胎培养液中添加0.5 mmol/L HTAU孤雌胚发育最好。     

母猪的生殖生理因素

1母猪的性发育与繁殖生理 1.1生殖器官发育 1.1.1卵巢发育 主要在胚胎期进行,从胚胎的50 d正式开始到出生后1月龄左右(断奶).这样的卵母细胞和原始卵泡细胞发育是不需要类固醇激素的激活的. 1.1.2卵泡、子宫、生殖道发育 主要在出生后70- 140日龄,这时需要雌激素激活. 1.2繁殖生理过程的激素调控 1.2.1发情 当卵巢大量卵泡发育成熟时,这些卵泡的雌二醇分泌增加,延长了下丘脑促性腺激素释激素的释放,GnRH促进卵巢促黄体素的分泌;在此过程中,雌二醇同时促进发情行为和生殖器官形态改变,即有了发情的外观特征,以静立反射为发情是否开始的识别.     

miRNA调控哺乳动物卵泡发育和卵母细胞成熟的研究进展

雌性哺乳动物的卵泡发育和卵母细胞成熟受繁殖关键基因的时空调控,miRNA作为一类小的非编码RNA,调节大部分此类基因的表达。近十几年来,研究者通过高通量测序、敲除miRNA生成过程中的关键基因以及过表达或抑制miRNA表达等方法找到了大量与哺乳动物卵泡发育和卵母细胞生长相关的miRNAs。通过研究这些miRNAs及其靶基因的互作关系,最终确定其在哺乳动物卵泡发育和卵母细胞成熟中的作用。本文综述了雌性哺乳动物主要生殖细胞及细胞外miRNAs在卵泡发育和卵母细胞成熟过程中的表达及潜在作用,以期为深入探究雌性哺乳动物繁殖调控机制提供参考。     

GDF9/BMP15对卵泡发育的调控

卵母细胞及其紧密连接的卵泡细胞之间的精细调节,促使卵母细胞成熟、受精和胚胎发育.在卵泡发育过程中,除了下丘脑-垂体-性腺轴间的内分泌调节外,卵母细胞源旁分泌或自分泌因子维持发育卵泡内微环境稳态,调节卵母细胞成熟和颗粒细胞增殖.目前发现,这些关键的调控因子主要是TGFβ超家族成员中的生长分化因子-9 （GDF9）和骨形态发生蛋白（BMP15）.GDF9/BMP15主要表达于卵母细胞,是卵泡发育必需的细胞因子.论文综述了GDF9/BMP15的结构特点、表达特性、信号通路及其在卵巢中的生物学作用等研究进展.     

生长因子家族对哺乳动物胚胎着床的调控

哺乳动物胚胎早期发育和着床是一个非常复杂的过程,受到多种因子的调控。其中生长因子如表皮生长因子、成纤维细胞生长因子、转化生长因子β和胰岛素样生长因子等在调控过程中发挥着重要的作用。本文就这几种生长因子的特点及其调控胚胎着床的机制作一综述。     

哺乳动物腔前卵泡的分离与培养

哺乳动物卵巢中绝大多数卵母细胞以无腔形式存在，有腔卵泡所占比例很少。通过建立腔前卵泡的培养体系，获取大量的具有成熟和受精能力的卵母细胞，将极大地促进体外受精、核移植等胚胎工程技术的发展，并有利于研究卵泡和卵母细胞的发育规律。     

The localization and expression of epidermal growth factor and epidermal growth factor receptor in bovine ovary during oestrous cycle

Epidermal growth factor (EGF) is one of the important regulatory factors of EGF family. EGF has been indicated to effectively inhibit the apoptosis of follicular cells, to promote the proliferation of granulosa cells and the maturation of oocytes, and to induce ovulation process via binding to epidermal growth factor receptor (EGFR). However, little is known about the distribution and expression of EGF and EGFR in cattle ovary especially during oestrous cycle. In this study, the localization and expression rule of EGF and EGFR in cattle ovaries of follicular phase and luteal phase at different time points in oestrous cycle were investigated by using IHC and real-time qPCR. The results showed that EGF and EGFR in cattle ovary were mainly expressed in granulosa cells, cumulus cells, oocytes, zona pellucida, follicular fluid and theca folliculi externa of follicles. The protein and mRNA expression of EGF/EGFR in follicles changed regularly with the follicular growth wave both in follicular and in luteal phase ovaries. In follicular phase ovaries, the protein expression of EGF and EGFR was higher in antral follicles than that of those in other follicles during follicular growth stage, and the mRNA expression of EGFR was also increased in stage of dominant follicle selection. However, in luteal phase ovaries, the growth of follicles was impeded during corpus luteum development under the action of progesterone secreted by granular lutein cell. The mRNA and protein expressions of EGF and EGFR in ovarian follicles during oestrous cycle indicate that they play a role in promoting follicular development in follicular growth waves and mediating the selection process of dominant follicles.     

The efficiency of in vitro ovine embryo production using an undefined or a defined maturation medium is determined by the source of the oocyte

In vitro oocyte maturation can be influenced by oocyte source and maturation media composition. The aim of the present study was to compare the efficiency of a defined in vitro maturation medium (TCM199 supplemented with cysteamine and epidermal growth factor; Cys + EGF) with an undefined medium (TCM199 supplemented with follicle-stimulating hormone and follicular fluid; FSH + FF) for in vitro production (IVP) of ovine embryos, using oocytes obtained by laparoscopic ovum pick-up from FSH-stimulated [n=11; 158 cumulus-oocyte complexes (COCs)] and non-stimulated (n=16; 120 COCs) live ewes, as well as abattoir-derived oocytes (170 COCs). The produced blastocysts were vitrified and some of them were transferred to synchronized recipients. The best and the worst final yields of embryo IVP observed in this study were obtained using oocytes from FSH-stimulated ewes matured in FSH + FF (41.3%; 33/80) and in Cys + EGF (19.2%; 15/78) medium, respectively (p<0.01). No significant differences between both media were attained in the blastocyst development rate or in the final yield of embryo IVP using oocytes from non-stimulated ewes or abattoir-derived oocytes. The overall in vivo survival rate of the transferred vitrified blastocysts was 13.1% (8/61), without significant differences between oocyte sources or maturation media. In conclusion, under the experimental conditions of the present study, TCM199 supplemented with cysteamine and EGF is a convenient defined maturation medium for IVP of embryos from oocytes of live non-stimulated ewes or from oocytes of abattoir-derived ovaries. However, the best final yield of embryo IVP observed in this study was attained when oocytes came from FSH-stimulated donors and TCM199 was supplemented with FSH and follicular fluid.     

High-resolution ultrasonography of xenografted domestic cat ovarian cortex

Transplantation of ovarian tissue has high potential for female gamete conservation. However, optimal timing of oocyte recovery for in vitro maturation and fertilization is still critical. Therefore the aim of the present study was to use high-resolution transcutaneous ultrasonography to monitor follicular development within xenografted ovarian tissue. Ovarian cortex fragments (n=44) from domestic cats were transplanted into athymic nude rats (n=12). Graft development in the animals was assessed weekly by high frequency ultrasound (10-22 MHz) under two different FSH regimes. Blood collection for serum estradiol determination and vaginal smears were performed simultaneously. The xenografts were removed at different time points according to the ultrasound findings. The survival rate of the transplants 4 weeks after surgery was 54.5% and antral follicular growth was observed within 10 grafts from 5 different hosts (8.6 +/- 6.43 follicles per graft). Early follicle antrums could be detected from 0.4 mm onwards. The growth rate of the antral cavity was calculated from weekly measurements (0.56 +/- 0.44 mm per week). Although vaginal cells and estradiol levels followed a cyclic pattern, no correlation was found between follicular diameter, estradiol and keratinized vaginal cells. We recovered 5, 1 and 4 cumulus oocyte complexes from three different individuals during weeks 19, 21, and 23 respectively. Extrusion of a polar body (1 oocyte) and germinal vesicle break down (7 oocytes) indicated progression of maturation after in vitro culture. We conclude that ultrasonography und provided a reliable method to examine xenograft survival and follicular development within the grafts. Furthermore, this technique is suitable for assessment of the efficiency of hormonal treatment and narrowing of the optimal time frame for oocyte retrieval. To our knowledge, this is the first report of the in vivo development of early antral follicles in mammalian species.     

表皮生长因子和胰岛素样生长因子对水牛卵母细胞胞质成熟的影响

以皮层颗粒（CG）单层分布于质膜下做为卵母细胞胞质成熟的标志,利用CG荧光染色法,研究了不同浓度表皮生长因子（EGF）和胰岛素样生长因子（IGF-1）及其组合对水牛卵母细胞胞质成熟的影响。结果发现：（1）添加不同浓度的EGF（10、20、30、50ng／mL）都可以提高胞质的成熟率,但是组间差异不显著（P〉0．05）;皮质颗粒的分布随着EGF浓度的升高逐步由中间分布向皮层分布转变;（2）在成熟液中添加IGF-130ng／mL时效果较好,能显著提高卵母细胞胞质的成熟率;皮质颗粒的分布随着IGF-1浓度的升高逐步由中间分布向皮层分布转变,在添加IGF一130ng／mL时,在皮层分布最好,随着IGF-1量的进一步增加,皮质颗粒又向中间分布转变;（3）添加20ng／mL EGF＋30ng／mL IGF-1组卵母细胞体外成熟率高于添加30ng／mL的IGF-1组,显著高于添加20ng／m LEGF组和对照组（P〈0.05）。由此表明,EGF和IGF-1对水牛卵母细胞体外成熟有协同作用。     

Bmp/Smad信号通路及其在哺乳动物卵巢发育中的作用

开展绵羊多羔性状基因的研究对于揭示其分子调控机制和提高绵羊繁殖力具有重要意义。骨形态发生蛋白(BMPs)为转化生长因子-β(TGF-β)超家族成员,与哺乳动物繁殖活动密切相关。研究表明,BMPs可促使原始卵泡向次级卵泡转化,对哺乳动物卵巢颗粒细胞增殖、生殖激素的合成和分泌以及卵母细胞成熟和排卵等方面起重要调节作用,而BMPs发挥功能主要依赖于经典的Bmp/Smad信号通路。本文就Bmp/Smad信号通路成员的表达、对早期胚胎发育的影响以及在哺乳动物卵巢发育中的作用等方面的研究进行总结,以期为进一步研究BMPs及其信号通路的调控机制提供参考。     

Cyclopamine did not affect mouse oocyte maturation in vitro but decreased early embryonic development

Hedgehog (Hh) pathway has been studied in various animal body life procedures and is suggested to be important for the development of multiple organs. The genes involved in the Hh signaling pathway were expressed in the ovary of mice, pigs and cattle. However, the function of Hh signaling pathway on oocyte maturation and early embryonic development is still controversial. We detected the effect of sonic hedgehog (Shh) and cyclopamine on the in vitro maturation of mouse oocytes and embryo development. The results showed that the presence of Shh or cyclopamine resulted in similar oocyte maturation to control groups. Shh did not improve early embryonic development. However, the supplement of cyclopamine depressed early embryo development. The mRNA of shh, ptch1, smo and gli1 were less detected in the denuded oocytes. The expression levels of ptch1 ascended from the uncleaved zygote to blastocyst stage. Smo or gli1 were expressed on a higher level at the two‐cell or four‐cell stage in early embryonic development separately. Therefore, Shh did not affect mouse oocyte maturation and early embryo development, but cyclopamine led to inhibited development of mouse early embryo. The effects of Hh signaling on the oocyte maturation and early embryo development might be species‐specific.     

Effect of Human Menopausal Gonadotropin,17β-estradiol and Epidermal Growth Factor on the Quality of in vitro Maturation Bovine Oocytes

For optimizing in vitro maturation system of bovine oocytes,we firstly examined the influence of four different hormonal regimes(FSH+LH,HMG,FSH+LH+E₂ and HMG+E₂) on oocyte maturation rates.Then we studied the effects of epidermal growth factor (EGF) in the above defined medium on bovine oocyte maturation,in vitro development and quality of parthenogenetic embryos.The cell apoptotic index of parthenogenetic blastocysts was detected by TUNEL.No significant difference was observed in maturation rates in four groups supplemented with different hormones.However,human menopausal gonadotropin (HMG) provided steady maturation results in replicates.Maturation of oocytes was promoted by supplementation with 17β-estradiol (E₂).Combination of HMG and E₂ gave rise to steady and efficient mature results.The presence of EGF at 30 ng/mL concentration significantly increased maturation rate and blastocyst rate and reduced apoptotic cells in parthenogenetic blastocysts.Therefore,the optimal oocyte maturation solution could be supplemented with 0.075 IU/mL HMG,1 μg/mL E₂ and 30 ng/mL EGF.     

Oocyte-somatic cell-endocrine interactions in pigs

Oocyte-somatic cell communication is bi-directional and essential for both oocyte and follicular granulosa and theca cell function and development. We have shown that the oocyte secretes factors that stimulate porcine granulosa cell proliferation in serum-free culture, and suppress progesterone production, thereby preventing premature luteinisation. Possible candidates for mediating some of these effects are the bone morphogenetic proteins (BMPs) that belong to the transforming growth factor beta family. They are emerging as a family of proteins critical for fertility and ovulation rate in several mammals, and they are expressed in various cell types in the ovary. We have evidence for a functional BMP system in the porcine ovary and BMP receptors are present in the egg nests in the fetal ovary and in the granulosa cells, oocytes and occasional theca cells throughout subsequent development. In addition to paracrine interactions in the ovary, the porcine oocyte and its developmental potential can also be influenced by nutritional manipulation in vivo. We have demonstrated that feeding a high plane of nutrition to gilts for 19 days prior to ovulation increased oocyte quality compared to control animals fed a maintenance diet, as determined by oocyte maturation in vitro. This was associated with a number of changes in circulating reproductive and metabolic hormones and also in the follicular fluid in which the oocyte is nurtured. Further studies showed a similar increase in prenatal survival on Day 30 of gestation, demonstrating a direct link between oocyte quality/maturation and embryo survival. Collectively, these studies emphasise the importance of the interactions that occur between the oocyte and somatic cells and also with endocrine hormones for ovarian development, and ultimately for the production of oocytes with optimal developmental potential.     

Protein Synthesis during Maturation of Bovine Oocytes, Effect of Epidermal Growth Factor

The objective of this study was to determine whether epidermal growth factor (EGF) affected protein synthesis in oocytes during maturation. Initially, the effect of EGF on oocyte maturation was examined to ensure that there was a beneficial effect of EGF in the protein-free maturation medium used in these studies. Results showed that the presence of EGF during maturation significantly enhanced cleavage rate and development to the blastocyst stage. Development after maturation in the presence of EGF was similar to that seen in medium containing serum, luteinizing hormone, follicle-stimulating hormone and estradiol. Protein synthesis was examined in immature oocytes and after 16 or 24 h maturation. Oocytes from each group were labelled by incubation for 4 h with ³⁵S-methionine, the proteins were then separated by two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Between 400 and 500 proteins could be separated using this method and marked changes in protein synthesis was observed during maturation. Changes in eight different proteins were observed when protein patterns from oocytes matured for 16 h with and without EGF were compared. These results suggest that EGF plays a physiological role in oocyte maturation and identification of the proteins induced by EGF could be important for improving our understanding of oocyte maturation in vitro .     

Kit和KitL在卵泡发育过程中的作用

在卵泡内,卵母细胞及其周围的颗粒细胞之间的旁分泌作用对哺乳动物的卵子发生和卵泡发育是非常重要的。研究表明颗粒细胞衍生的KitL(Kitligand,stem cell factor,SCF)与卵母细胞和膜细胞产生的Kit的相互作用在PGCs迁移和增殖、卵泡发育过程中有重要的作用。本文重点阐述了由KitL通过Kit激活的PI3K(phosphatidylinositol 3-kinase,磷脂酰肌醇-3-激酶)通路,它对卵母细胞生长、凋亡和卵泡早期发育起重要的调节作用。