Ward F, Rizos D, Corridan D, Quinn K, Boland M, Lonergan P
Department of Animal Science and Production and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Lyons Research Farm, Newcastle, County Dublin, Ireland.
Mol Reprod Dev. 2001 Sep;60(1):47-55. doi: 10.1002/mrd.1060.
The objectives of this study were: (1) to evaluate the effect of sire on the time from insemination to first cleavage following insemination in vitro and the relationship of this parameter to field fertility and (2) to establish the relationship between the kinetics of cleavage in vitro and oocyte developmental competence for bulls of known field fertility. Frozen semen from six bulls with 150-day non-return rates ranging from 57-78% was used. In experiment 1, after insemination with semen from one of the six bulls, presumptive zygotes were transferred to IVC in droplets of synthetic oviduct fluid. Droplets were examined at 24, 27, 30, 33, 36, 42, and 48 hr after insemination and the number of cleaved oocytes was recorded. Blastocyst yield was recorded on Days 6-, 7-, and 8-post insemination. In experiment 2, culture droplets were examined at 30, 36, and 48 hr after insemination. At each time point, the number of cleaved embryos was recorded and these embryos were transferred into new droplets and were cultured separately for the duration of the experiment. The proportion of embryos developing to the blastocyst stage was recorded for each of the groups for each bull. The best predictor of field fertility was a model containing 33-hpi-cleavage percentage only (r = 0.689, P < 0.0001). There was also a significant correlation between blastocyst yield and non-return rate, with Day 7 blastocyst yield having the highest correlation (r = 0.356), although this was relatively low in comparison. In experiment 2, irrespective of sire, a significantly higher proportion of those early-cleaving oocytes (before 30 hpi) developed to blastocysts than those cleaving later. In most cases, a higher proportion of blastocysts derived from early-cleaving oocytes hatched from the zona pellucida suggesting that such blastocysts are of superior quality to those derived from late-cleaving oocytes. In conclusion these data confirm our earlier observations that earliest cleaving zygotes are more competent in terms of development to the blastocyst stage than those that cleave later. This phenomenon is independent of the sire used. However, we have demonstrated that the kinetics of early embryonic development as measured by the timing of the first cleavage division post insemination vary between different bulls and that these differences can be used to discriminate between bulls of high and low bull field fertility.
（1）评估种公牛对体外受精后至首次卵裂时间的影响，以及该参数与田间繁殖力的关系；（2）确定已知田间繁殖力的公牛体外卵裂动力学与卵母细胞发育能力之间的关系。使用了6头种公牛的冷冻精液，其150天不返情率在57%-78%之间。在实验1中，用6头种公牛之一的精液进行受精后，将推定的受精卵转移到合成输卵管液滴中进行体外培养。在受精后24、27、30、33、36、42和48小时检查液滴，并记录卵裂的卵母细胞数量。在受精后第6、7和8天记录囊胚产量。在实验2中，在受精后30、36和48小时检查培养液滴。在每个时间点，记录卵裂胚胎的数量，并将这些胚胎转移到新的液滴中，在实验期间分别培养。记录每头种公牛每组胚胎发育到囊胚阶段的比例。田间繁殖力的最佳预测指标是仅包含33小时受精后卵裂百分比的模型（r = 0.689，P < 0.0001）。囊胚产量与不返情率之间也存在显著相关性，第7天的囊胚产量相关性最高（r = 0.356），尽管相对较低。在实验2中，无论种公牛如何，早期卵裂的卵母细胞（受精后30小时之前）发育成囊胚的比例显著高于后期卵裂的卵母细胞。在大多数情况下，来自早期卵裂卵母细胞的囊胚有更高比例从透明带孵化出来，这表明此类囊胚的质量优于来自后期卵裂卵母细胞的囊胚。总之，这些数据证实了我们早期的观察结果，即最早卵裂的合子在发育到囊胚阶段方面比后期卵裂的合子更有能力。这种现象与所用的种公牛无关。然而，我们已经证明，通过受精后首次卵裂分裂的时间来衡量的早期胚胎发育动力学在不同种公牛之间存在差异，并且这些差异可用于区分田间繁殖力高和低的种公牛。
