Yang Xin Yu, Jia Zhen Wei
College of Animal Science and Technology, Inner Mongolia University for the Nationalities, Tongliao 028043, China.
Yi Chuan. 2019 Feb 20;41(2):137-145. doi: 10.16288/j.yczz.18-193.
The surge of luteinizing hormone (LH) in preovulatory ovarian follicles triggers the resumption of meiosis in oocytes and induces the proliferation of surrounding cumulus granulosa cells. It is believed that LH receptors are expressed in the mural granulosa cells, but not the oocytes and the surrounding cumulus cells, suggesting that the LH signaling is mediated by factors produced by the granulosa cells. However, the mechanism underlying oocyte maturation induced by LH before ovulation has been controversial. Current studies suggest that LH binds on to its receptor on granulosa cells of the follicular wall to promote the production of EGF-like factors, which activate various signaling cascades and induce oocyte maturation and development. Since the in vitro maturation system is difficult to simulate the in vivo physiological environment, in vitro cultured follicles are likely to be de?cient in the EGF-like factors, which could result in the poor developmental competency of in vitro cultured oocytes and restrict their efficient utilization. In this review, we summarize the EGF-like factor signaling system in granulosa cells and its regulation of oocyte maturation and development. It aims to optimize the in vitro maturation culture system of oocytes and increase the EGF-like factor signaling system in cumulus granulosa cells, thereby providing a framework for improving the efficiency on in vitro maturation of oocytes.
排卵前卵巢卵泡中促黄体生成素（LH）的激增会触发卵母细胞减数分裂的恢复，并诱导周围卵丘颗粒细胞的增殖。据信，LH受体在壁层颗粒细胞中表达，但在卵母细胞和周围的卵丘细胞中不表达，这表明LH信号是由颗粒细胞产生的因子介导的。然而，排卵前LH诱导卵母细胞成熟的机制一直存在争议。目前的研究表明，LH与其在卵泡壁颗粒细胞上的受体结合，以促进表皮生长因子（EGF）样因子的产生，这些因子激活各种信号级联反应并诱导卵母细胞成熟和发育。由于体外成熟系统难以模拟体内生理环境，体外培养的卵泡可能缺乏EGF样因子，这可能导致体外培养的卵母细胞发育能力较差，并限制其有效利用。在这篇综述中，我们总结了颗粒细胞中的EGF样因子信号系统及其对卵母细胞成熟和发育的调节。其目的是优化卵母细胞的体外成熟培养系统，并增加卵丘颗粒细胞中的EGF样因子信号系统，从而为提高卵母细胞体外成熟效率提供一个框架。
