Department of Genetics and Animal Breeding, Poznan University of Life Sciences, Poznan, Poland.
Reprod Biol. 2013 Mar;13(1):82-7. doi: 10.1016/j.repbio.2013.01.180. Epub 2013 Feb 8.
Information gained from most human studies indicate a negative correlation between the apoptotic index (AI) in cumulus cells (CC) and the quality of the corresponding oocytes. However, results obtained in other species are not so consistent. The rate of apoptosis-free COCs (cumulus oocytes complexes) subjected to IVM (in vitro maturation) also varies among studies. The aim of the present study was to investigate whether the AI in cumulus cells of post-IVM COCs is related to the morphology of pre-IVM COCs and to meiotic competence of bovine oocytes. COCs of known morphology (four grade scale) obtained from individual follicles were matured in a well-in-drop system. After IVM, the external layers of CC of each COC were analyzed by TUNEL. In order to determine the meiotic stage, oocytes were stained with DAPI. It was found that 25.6% of bovine COCs contained apoptosis-free cumulus cells. Moreover, the majority of COCs with apoptotic cells were characterized by apoptotic index lower than 15%. The level of apoptosis in CC was related neither to COC morphology nor to the oocyte meiotic stage. It is suggested that the extent of apoptosis in cumulus cells is not a reliable quality marker of the corresponding oocyte after IVM.
从大多数人类研究中获得的信息表明，卵丘细胞（CC）中的细胞凋亡指数（AI）与相应卵母细胞的质量呈负相关。然而，其他物种的研究结果并不那么一致。在体外成熟（IVM）过程中无凋亡的 COC（卵丘卵母细胞复合物）的比例在不同研究中也有所不同。本研究旨在探讨 IVM 后 COC 中 CC 的 AI 是否与 IVM 前 COC 的形态和牛卵母细胞的减数分裂能力有关。从单个卵泡中获得具有已知形态（四级评分）的 COC 在液滴培养系统中进行成熟。IVM 后，通过 TUNEL 分析每个 COC 的 CC 的外层。为了确定减数分裂阶段，用 DAPI 对卵母细胞进行染色。结果发现，25.6%的牛 COC 含有无凋亡的卵丘细胞。此外，大多数含有凋亡细胞的 COC 的凋亡指数低于 15%。CC 中的凋亡水平既与 COC 形态也与卵母细胞减数分裂阶段无关。因此，推测 IVM 后 CC 中的凋亡程度不是相应卵母细胞的可靠质量标志物。
