Sato E, Matsuo M, Miyamoto H
Kyoto University, Japan.
J Anim Sci. 1990 Apr;68(4):1182-7. doi: 10.2527/1990.6841182x.
The present study was undertaken to determine the precise stage of growth at which the ability to resume meiosis is acquired in bovine oocytes. Oocytes of various sizes were isolated from ovaries by mechanical dissection using an 18-gauge needle followed by a razor blade. This method yielded an average of 26.2 +/- 7.4 growing and fully grown oocytes from an ovary. Cumulus-enclosed oocytes were cultured in vitro in tissue culture medium 199 containing 10% fetal calf serum. Oocytes less than or equal to 90 microns in diameter did not resume meiosis. However, germinal vesicle breakdown was observed in oocytes whose diameters exceeded 91 microns. Polar body formation was observed in oocytes with diameters exceeding 101 microns. About 80% of the oocytes with diameters greater than or equal to 121 microns were able to extrude the polar body. The percentage of large oocytes (101 to 120 microns) with first polar body increased when incubated in medium containing dibutyryl cyclic adenosine 3',5'-monophosphate; however, oocytes 90 to 101 microns did not extrude the first polar body even when cultured in a medium containing dibutyryl cyclic adenosine 3',5'-monophosphate. These observations indicate that the capability to resume meiosis is acquired gradually during development of oocytes and that dibutyryl cyclic adenosine 3',5'-monophosphate can improve the meiotic competence of bovine oocytes in culture.
本研究旨在确定牛卵母细胞获得恢复减数分裂能力时的确切生长阶段。使用18号针头，随后用剃须刀片通过机械解剖从卵巢中分离出各种大小的卵母细胞。该方法平均从一个卵巢中获得26.2±7.4个正在生长和完全成熟的卵母细胞。将卵丘包裹的卵母细胞在含有10%胎牛血清的组织培养基199中进行体外培养。直径小于或等于90微米的卵母细胞不能恢复减数分裂。然而，在直径超过91微米的卵母细胞中观察到了生发泡破裂。在直径超过101微米的卵母细胞中观察到了极体形成。直径大于或等于121微米的卵母细胞中约80%能够排出极体。当在含有二丁酰环腺苷3',5'-单磷酸的培养基中孵育时，带有第一极体的大卵母细胞（101至120微米）的百分比增加；然而，即使在含有二丁酰环腺苷3',5'-单磷酸的培养基中培养，90至101微米的卵母细胞也不会排出第一极体。这些观察结果表明，恢复减数分裂的能力在卵母细胞发育过程中逐渐获得，并且二丁酰环腺苷3',5'-单磷酸可以提高培养的牛卵母细胞的减数分裂能力。
