Kölle Sabine, Dubois Clotilde S, Caillaud Maud, Lahuec Cécile, Sinowatz Fred, Goudet Ghylène
Institute of Veterinary Anatomy, University of Giessen, Giessen, Germany.
Mol Reprod Dev. 2007 Jul;74(7):851-9. doi: 10.1002/mrd.20501.
In the equine, the zona pellucida (ZP) is the major barrier to successful in vitro fertilization. Therefore the aim of our studies was to analyze species-specific features of the equine ZP in regard to structure and glycoprotein ZPB and ZPC expression sites during oocyte development and embryogenesis. The equine ZP revealed high immunological cross-reactivity to porcine ZPB and ZPC. In the ovary, the distribution of ZPB and ZPC was co-localized and correlated with the developmental stage of the follicle. ZPB and ZPC expression started in the oocyte of the late primordial and primary follicle. In the secondary follicle, both the oocyte and the cumulus cells contributed to ZPB and ZPC synthesis. After in vivo maturation the oocyte stopped ZPB and ZPC production whereas the cumulus cells continued synthesis. Contrary, in vitro matured (IVM) cumulus-oocyte-complexes (COCs) revealed a reverse expression pattern. This was correlated to alterations in the distribution, number, and size of pores in the ZP. In the zona, N-acetylglucosamine residues were co-localized with ZPC. The acellular glycoprotein capsule surrounding early equine embryos was negative for ZPB and ZPC. Our results imply that in the horse ZPB and ZPC glycoprotein expression is differentially regulated during folliculogenesis, oocyte maturation, and embryogenesis. Contrary to the bovine and porcine, zona protein synthesis during in vivo maturation is completely overtaken by the cumulus cells implying that in the horse these cells are crucial for zona integrity. During IVM, the cumulus cells lose their ability to synthesize glycoproteins leading to alterations in the zona structure.
在马属动物中，透明带（ZP）是体外受精成功的主要障碍。因此，我们研究的目的是分析马属动物ZP在卵母细胞发育和胚胎发生过程中结构以及糖蛋白ZPB和ZPC表达位点的物种特异性特征。马属动物的ZP对猪的ZPB和ZPC显示出高度免疫交叉反应性。在卵巢中，ZPB和ZPC的分布共定位，并与卵泡的发育阶段相关。ZPB和ZPC的表达始于原始卵泡晚期和初级卵泡的卵母细胞。在次级卵泡中，卵母细胞和卵丘细胞都参与ZPB和ZPC的合成。体内成熟后，卵母细胞停止ZPB和ZPC的产生，而卵丘细胞继续合成。相反，体外成熟（IVM）的卵丘-卵母细胞复合体（COC）显示出相反的表达模式。这与ZP中孔的分布、数量和大小的改变相关。在透明带中，N-乙酰葡糖胺残基与ZPC共定位。围绕早期马属动物胚胎的无细胞糖蛋白囊对ZPB和ZPC呈阴性。我们的结果表明，在马中，ZPB和ZPC糖蛋白的表达在卵泡发生、卵母细胞成熟和胚胎发生过程中受到差异调节。与牛和猪相反，体内成熟过程中透明带蛋白的合成完全由卵丘细胞接管，这意味着在马中这些细胞对透明带的完整性至关重要。在IVM期间，卵丘细胞失去合成糖蛋白的能力，导致透明带结构改变。
