Department of Biology, University of Dayton, Dayton, Ohio, USA.
Theriogenology. 2013 Sep 15;80(5):498-506. doi: 10.1016/j.theriogenology.2013.05.013. Epub 2013 Jun 18.
The aim of this study was to analyze surface morphology of the zona pellucida (ZP) and assess its relationship with oocyte viability, cumulus-oocyte complex (COC) quality, and oocyte donor age in dogs. Canine ovaries were sliced to release COCs for use in three experiments. In Experiment 1, oocytes from high-quality (grade I) COCs were viewed with scanning electron microscopy to visualize the zona surface. Four zonae, classified as types I, II, III, and IV, were detectable on high-quality oocytes. Most (95.5%) dog donors had oocytes with two or three ZP types. The ZP type I had a smooth compact surface with few pores. The ZP type II was less compact with many distinct circular or elliptical pores. The ZP type III had a rough surface with folds and many irregular shaped pores and hollows. The ZP type IV also had a rough surface with folds, but in addition, stringy filaments obscured the pores and hollows. The frequency of ZP type I in the oocyte population was low (2.7%), whereas ZP types II, III, and IV each occurred in approximately one-third of the oocyte population. In Experiment 2, oocytes from high-quality COCs were stained with propidium iodide (PI) before scanning electron microscopy to investigate the relationship of oocyte viability with ZP morphology. In Experiment 3, oocytes were collected from low-quality (grade 2) and high-quality (grade 1) COCs to investigate the role of COC quality on zona structure. Zonae types I and II were characteristic of PI-positive (dead) oocytes and oocytes from low-quality COCs, whereas ZP types III and IV were prevalent on PI-negative (living) oocytes and oocytes from high-quality COCs. We concluded that the heterogeneous ZP surface underwent structural rearrangements related to oocyte viability and COC quality. This warrants further investigation into ZP structure and may be useful for canine-assisted reproduction.
本研究旨在分析透明带（ZP）的表面形态，并评估其与卵母细胞活力、卵丘-卵母细胞复合物（COC）质量和供体犬年龄的关系。犬卵巢切片以释放 COC 用于三项实验。在实验 1 中，使用扫描电子显微镜观察来自高质量（I 级）COC 的卵母细胞，以可视化透明带表面。在高质量卵母细胞上可检测到四种透明带类型，分为 I、II、III 和 IV 型。大多数（95.5%）犬供体的卵母细胞具有两种或三种 ZP 类型。ZP 类型 I 具有光滑致密的表面，孔较少。ZP 类型 II 不那么致密，有许多明显的圆形或椭圆形孔。ZP 类型 III 表面粗糙，有褶皱和许多不规则形状的孔和凹陷。ZP 类型 IV 表面也有褶皱，但此外，丝状纤维使孔和凹陷模糊不清。卵母细胞群体中 ZP 类型 I 的频率较低（2.7%），而 ZP 类型 II、III 和 IV 分别存在于卵母细胞群体的约三分之一中。在实验 2 中，使用碘化丙啶（PI）对来自高质量 COC 的卵母细胞进行染色，然后进行扫描电子显微镜检查，以研究卵母细胞活力与 ZP 形态的关系。在实验 3 中，从低质量（II 级）和高质量（I 级）COC 中收集卵母细胞，以研究 COC 质量对透明带结构的作用。ZP 类型 I 和 II 是 PI 阳性（死亡）卵母细胞和低质量 COC 卵母细胞的特征，而 ZP 类型 III 和 IV 则存在于 PI 阴性（存活）卵母细胞和高质量 COC 卵母细胞上。我们得出结论，异质 ZP 表面发生了与卵母细胞活力和 COC 质量相关的结构重排。这需要进一步研究 ZP 结构，并且可能对犬辅助生殖有用。
