Localization of vascular endothelial growth factor in the zona pellucida of developing ovarian follicles in the rat: a possible role in destiny of follicles
Localization of vascular endothelial growth factor in the zona pellucida of developing ovarian follicles in the rat: a possible role in destiny of follicles
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DOI：
10.1007/s00418-003-0586-4
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发表时间：
2003-11-01
影响因子：
2.3
通讯作者：
Demir, R
中科院分区：
文献类型：
--
作者：
Celik-Ozenci, C;Akkoyunlu, G;Demir, R
越来越多的证据表明，在许多物种中，血管生成因子，如血管内皮生长因子和碱性成纤维细胞生长因子，可能在卵泡发生中发挥重要作用。本研究的目的是确定血管内皮生长因子及其受体Flt-1和KDR在大鼠卵巢中的定位，以及碱性成纤维细胞生长因子在卵巢中的表达，并探讨其在不同卵泡发育阶段的分布。在20只处女大鼠中，10只在自然卵巢周期中进行研究，没有任何排卵诱导。对其余10只进行超数排卵，并对其卵巢进行蛋白质分析和免疫组织化学研究。原始卵泡的颗粒细胞(GC)和卵母细胞均为阴性。在早期初级卵泡中，卵母细胞中存在VEGF，但其免疫反应较弱，而新发育的初级卵泡的透明带(ZP)中未检测到VEGF。随后，随着次级卵泡GC之间的窦隙的开始，一些次级卵泡的ZP开始呈强阳性表达，并在卵母细胞周围形成一个连续的环。在排卵前成熟卵泡中，颗粒细胞和内膜(TI)细胞呈弱阳性反应。Western印迹分析还表明，卵泡中存在一种26 kDa的蛋白质--血管内皮生长因子。此外，在排卵的卵丘-卵母细胞复合体中，我们观察到在完全成熟的卵母细胞周围有一种晕状的VEGF免疫反应。生长卵泡中Flt-1和KDR受体的免疫反应主要局限于GC和TI细胞。各期卵泡的ZP内均未见抗bFGF免疫反应。在不同发育阶段的卵泡GC中表达较弱，但在有腔卵泡的毛细血管和间质血管中有一定程度的表达。有趣的是，在一些次级卵泡的ZP中，血管内皮生长因子免疫反应非常显著。因此，应考虑到血管内皮生长因子可能是主导卵泡选择或闭锁的重要调节分子。
There is increasing evidence that in many species angiogenic factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), may have important roles in folliculogenesis. The aim of this study is to determine the localization of VEGF and its receptors, Flt-1 and KDR, and bFGF expression in the rat ovary and to evaluate their distributions throughout the different follicular stages. Out of 20 virginal female rats, 10 were studied during the natural ovarian cycle without any ovulation induction. The other 10 were superovulated and their ovaries were studied by western analysis and immunohistochemistry. Granulosa cells (GC) and oocytes of primordial follicles were negative for VEGF. In early primary follicles, VEGF was present in the oocyte but its immunoreactivity was weak, while newly developing zona pellucida (ZP) of primary follicles was negative for VEGF. Subsequently, with the commencement of antral spaces between GC of the secondary follicle, ZP of some secondary follicles became strongly positive for VEGF, forming a continuous ring around the oocyte. In preovulatory mature follicles granulosa and theca interna (TI) cells showed a weak immunoreactivity for VEGF. Western blot analyses have also demonstrated that VEGF, a 26-kDa protein, was present in follicles. Moreover, in ovulated cumulus-oocyte complex we observed a halo-like immunoreactivity of VEGF around the fully mature oocyte. The immunoreactivity for Flt-1 and KDR receptors in growing follicles was mostly limited to GC and TI cells. Anti-bFGF did not exhibit any immunoreactivity in ZP of follicles at any stage. Its expression was weak in GC of the follicles at different stages, whereas, it could be localized to some extent in the blood capillaries of TI of antral follicles and in blood vessels localized in the stroma. Interestingly, VEGF immunoreactivity in the ZP of some secondary follicles is very striking. Accordingly, the possibility that VEGF may be an important regulatory molecule for the dominant follicle selection or atresia should be considered.