De La Fuente R, O'Brien M J, Eppig J J
The Jackson Laboratory, Bar Harbor, ME 04609, USA.
Hum Reprod. 1999 Dec;14(12):3060-8. doi: 10.1093/humrep/14.12.3060.
The objective of this study was to determine whether epidermal growth factor (EGF) promotes nuclear and cytoplasmic maturation of mouse oocytes grown in vivo or in vitro. In-vivo-grown oocytes were isolated at the germinal vesicle (GV) stage from gonadotrophin-primed (PR) or -unprimed (UPR) 22-day-old mice before in-vitro maturation (IVM). In-vitro-grown (IVG) oocytes were isolated from preantral follicles of 12-day-old mice and grown in vitro without gonadotrophins for 10 days before maturation (IVG/IVM oocytes). IVM and IVG/IVM oocytes were matured in medium supplemented with either EGF (10 ng/ml), follicle stimulating hormone (FSH) (100 ng/ml), EGF plus FSH, or with neither ligand (control). When oocyte-cumulus cell complexes were isolated from PR and UPR mice, IVM with EGF (10 ng/ml), alone or in combination with FSH (100 ng/ml), increased (P < 0.05) the incidence of nuclear maturation to metaphase II. Cytoplasmic maturation of oocytes from PR females, manifested as increased frequency of cleavage to the 2-cell stage and development to the blastocyst stage, was also enhanced with EGF (P < 0.05). Moreover, EGF increased the number of cells per blastocyst, but only in the absence of FSH (P < 0.01). In contrast, EGF, FSH, or EGF plus FSH did not affect the percentage of oocytes from UPR mice completing preimplantation development, but did increase the number of cells per blastocyst. These ligands also increased the proportion of IVG oocytes reaching metaphase II (53-57%) compared with controls (25%; P < 0.05). EGF alone or in combination with FSH increased (P < 0.05) the frequency of blastocyst formation (23% and 28%, respectively) compared with controls (13%). EGF treatment of maturing IVG oocytes produced blastocysts with more cells than other IVG groups (P < 0.05). It is concluded that gonadotrophins in vivo increase the sensitivity or responsiveness of cumulus cell-enclosed oocytes to EGF, thereby promoting both nuclear and cytoplasmic maturation. However, oocyte-granulosa cell complexes grown in vitro become responsive to EGF without gonadotrophin treatment. Thus, nuclear and cytoplasmic maturation of IVG oocytes is promoted by EGF treatment during meiotic maturation.
本研究的目的是确定表皮生长因子（EGF）是否能促进体内或体外培养的小鼠卵母细胞的核成熟和细胞质成熟。在体外成熟（IVM）前，从经促性腺激素预处理（PR）或未预处理（UPR）的22日龄小鼠的生发泡（GV）期分离体内生长的卵母细胞。体外培养（IVG）的卵母细胞从12日龄小鼠的窦前卵泡中分离出来，在无促性腺激素的情况下体外培养10天，然后进行成熟培养（IVG/IVM卵母细胞）。IVM和IVG/IVM卵母细胞在添加了EGF（10 ng/ml）、促卵泡激素（FSH）（100 ng/ml）、EGF加FSH或不添加任何配体（对照）的培养基中成熟。当从PR和UPR小鼠中分离卵母细胞-卵丘细胞复合体时，单独使用EGF（10 ng/ml）或与FSH（100 ng/ml）联合使用进行IVM，可提高（P<0.05）核成熟至中期II的发生率。PR雌性小鼠卵母细胞的细胞质成熟表现为分裂至2细胞期的频率增加以及发育至囊胚期，使用EGF也可增强这一过程（P<0.05）。此外，EGF增加了每个囊胚的细胞数量，但仅在无FSH的情况下（P<0.01）。相比之下，EGF、FSH或EGF加FSH并不影响UPR小鼠完成植入前发育阶段的卵母细胞百分比，但确实增加了每个囊胚的细胞数量。这些配体还增加了达到中期II的IVG卵母细胞的比例（53-57%），与对照组（25%）相比有显著差异（P<0.05）。与对照组（13%）相比，单独使用EGF或与FSH联合使用可提高（P<0.05）囊胚形成的频率（分别为23%和28%）。用EGF处理成熟的IVG卵母细胞产生的囊胚比其他IVG组的细胞更多（P<0.05）。研究得出结论，体内的促性腺激素增加了卵丘细胞包裹的卵母细胞对EGF的敏感性或反应性，从而促进核成熟和细胞质成熟。然而，体外培养的卵母细胞-颗粒细胞复合体在未经促性腺激素处理的情况下对EGF变得有反应。因此，在减数分裂成熟过程中，EGF处理可促进IVG卵母细胞的核成熟和细胞质成熟。
