Three experiments were conducted to determine influence of the bovine corpus luteum (CL) on morphometric and functional characteristics of oocytes, and subsequent embryonic development. Cumulus-oocyte complexes were aspirated from two types of cows: 1) with a CL in one ovary (CL+) and without a CL in the contralateral ovary (CL-), 2) and from cows without CL in either ovary (C). Intracellular activity of the enzyme glucose-6-phosphate dehydrogenase (G6PDH), oocyte diameter and thickness of the zona pellucida were determined (Experiment 1). Then, the rate of in vitro oocyte maturation for each ovarian category was evaluated and oocyte diameter and zona pellucida thickness were measured after maturation (Experiment 2). In Experiment 3, in vitro embryo production and cryotolerance were assessed. The oocyte diameter was greater (P < 0.01) and the zona pellucida was thinner in CL+ than in CL- (P > 0.05) or C (P = 0.0131) ovaries. Activity of G6PDH was lower in oocytes from CL+ than CL- (P < 0.01) and C (P = 0.0148) ovaries. Rate of oocyte maturation, oocyte diameter and thickness of the zona pellucida after maturation did not differ among groups. Rate of cleavage was greater in zygotes from CL+ than from CL- or C (P < 0.01); and CL+ ovaries produced more total embryos on day 7 (P < 0.05) and more blastocysts (P < 0.01) than CL- and C ovaries. Rate of expansion and hatching of day-7 vitrified-warmed blastocysts at 24 and 48 h of culture did not differ among groups. In conclusion, oocytes collected from CL+ ovaries were larger and metabolically more prepared to continue maturation than those from ovaries lacking a CL. Also, rates of cleavage and yield of blastocysts were greater for oocytes from CL+ ovaries than from CL- and C ovaries. These findings indicate that a CL influenced oocyte developmental competence and embryonic development, presumably through intraovarian interactions.

中文翻译：

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牛黄体对卵母细胞形态测定和发育能力、胚胎产生和低温耐受性的卵巢内影响

进行了三个实验来确定牛黄体 (CL) 对卵母细胞形态测量和功能特征以及随后的胚胎发育的影响。从两种类型的奶牛中抽吸出卵丘 - 卵母细胞复合物：1) 在一个卵巢中具有 CL (CL+) 并且在对侧卵巢中没有 CL (CL-)，2) 以及在任一卵巢中都没有 CL 的奶牛 (C)。测定了 6-磷酸葡萄糖脱氢酶 (G6PDH) 的细胞内活性、卵母细胞直径和透明带的厚度（实验 1）。然后，评估每个卵巢类别的体外卵母细胞成熟率，并在成熟后测量卵母细胞直径和透明带厚度（实验 2）。在实验 3 中，评估了体外胚胎生产和耐低温性。卵母细胞直径更大（P < 0. 01) 并且 CL+ 中的透明带比 CL- (P > 0.05) 或 C (P = 0.0131) 卵巢中的透明带更薄。来自 CL+ 的卵母细胞中 G6PDH 的活性低于来自 CL- (P < 0.01) 和 C (P = 0.0148) 卵巢的卵母细胞。卵母细胞成熟率、卵母细胞直径和成熟后透明带的厚度在各组之间没有差异。来自 CL+ 的受精卵的裂解率高于来自 CL- 或 C 的受精卵（P < 0.01）；和 CL+ 卵巢在第 7 天产生更多的总胚胎 (P < 0.05) 和比 CL- 和 C 卵巢更多的囊胚 (P < 0.01)。培养 24 小时和 48 小时时第 7 天玻璃化加热囊胚的膨胀和孵化率在各组之间没有差异。总之，与来自缺乏 CL 的卵巢的卵母细胞相比，从 CL+ 卵巢收集的卵母细胞更大，并且在代谢上更容易继续成熟。还，来自 CL+ 卵巢的卵母细胞的卵裂率和囊胚产量高于来自 CL- 和 C 卵巢的卵母细胞。这些发现表明 CL 影响了卵母细胞的发育能力和胚胎发育，大概是通过卵巢内的相互作用。