Rizos Dimitrios, Fair Trudee, Papadopoulos Serafeim, Boland Maurice P, Lonergan Patrick
Department of Animal Science and Production and Conway Institute for Biomedical and Biomolecular Research, University College Dublin, Lyons Research Farm, Newcastle, County Dublin, Ireland.
Mol Reprod Dev. 2002 Jul;62(3):320-7. doi: 10.1002/mrd.10138.
The objective of this study was to compare bovine and ovine oocytes in terms of (1) developmental rates following maturation, fertilization, and culture in vitro, (2) the quality of blastocysts produced in vitro, assessed in terms of their ability to undergo cryopreservation, and (3) the ultrastructural morphology of these blastocysts. In vitro blastocysts were produced following oocyte maturation/fertilization and culture of presumptive zygotes in synthetic oviduct fluid. In vivo blastocysts were used as a control from both species. In Experiment 1, the cleavage rate of bovine oocytes was significantly higher than that of ovine oocytes (78.3% vs. 58.0%, respectively, P < 0.001). The overall blastocyst yield was similar for both species (28.7% vs. 29.0%). However, when corrected for cleavage rate, significantly more ovine oocytes reached the blastocyst stage at all time-points (36.6% vs. 50.0% on day 8, for bovine and ovine, respectively, P < 0.001). Following vitrification, there was no difference in survival between in vivo produced bovine and ovine blastocysts (72 hr: 85.7% vs. 75.0%). However, IVP ovine blastocysts survived at significantly higher rates than IVP bovine blastocysts at all time points (72 hr: 47.4% vs. 18.1%, P < 0.001). At the ultrastructural level, compared with their in vivo counterparts, IVP blastocysts were characterized by a lack of desmosomal junctions, a reduction in the microvilli population, an increase in the average number of lipid droplets and increased debris in the perivitelline space and intercellular cavities. These differences were more marked in bovine IVP blastocysts, which also displayed electron-lucent mitochondria and large intercellular cavities. These observations may in part explain the species differences observed in terms of cryotolerance. In conclusion, the quality of ovine blastocysts was significantly higher than their bovine counterparts produced under identical in vitro conditions suggesting inherent species differences between these two groups affecting embryo quality.
本研究的目的是比较牛和羊的卵母细胞，具体包括：（1）成熟、受精和体外培养后的发育率；（2）体外产生的囊胚的质量，通过其冷冻保存能力进行评估；（3）这些囊胚的超微结构形态。卵母细胞成熟/受精后，将假定的受精卵在合成输卵管液中培养，从而产生体外囊胚。体内囊胚用作两个物种的对照。在实验1中，牛卵母细胞的分裂率显著高于羊卵母细胞（分别为78.3%和58.0%，P < 0.001）。两个物种的总体囊胚产量相似（分别为28.7%和29.0%）。然而，校正分裂率后，在所有时间点，更多的羊卵母细胞发育到囊胚阶段（第8天，牛和羊分别为36.6%和50.0%，P < 0.001）。玻璃化冷冻后，体内产生的牛和羊囊胚的存活率没有差异（72小时：85.7%对75.0%）。然而，在所有时间点，体外生产的羊囊胚的存活率显著高于体外生产的牛囊胚（72小时：47.4%对18.1%，P < 0.001）。在超微结构水平上，与体内囊胚相比，体外生产的囊胚的特征是缺乏桥粒连接、微绒毛数量减少、脂滴平均数量增加以及卵周间隙和细胞间腔中的碎片增加。这些差异在牛体外生产的囊胚中更为明显，其还表现出电子透明的线粒体和大的细胞间腔。这些观察结果可能部分解释了在冷冻耐受性方面观察到的物种差异。总之，在相同体外条件下产生的羊囊胚的质量显著高于牛囊胚，这表明这两组之间存在影响胚胎质量的固有物种差异。
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