次黄嘌呤维持小鼠卵母细胞减数分裂阻滞的时效性和可逆性研究

为提高体外成熟卵母细胞的发育能力,本实验采用卵泡内存在的减数分裂抑制剂次黄嘌呤(Hypoxanthine,HX)在体外维持小鼠GV期卵母细胞减数分裂阻滞,探讨了次黄嘌呤对卵母细胞减数分裂抑制作用的时效性、可逆性以及对卵丘扩展和解除抑制后的发育能力的影响。结果表明(1)4mmol/LHX维持减数分裂阻滞的作用具有时效性,GV%在18h时显著下降。(2)HX处理时间短于24h时,解除抑制后再成熟时卵母细胞的成熟率不受影响,抑制24h再成熟14h时成熟率仍可达86%。(3)HX处理会抑制卵丘扩展,解除抑制后再成熟时卵丘扩展程度跟抑制时间长短有关。(4)HX处理6h后,卵母细胞的孤雌激活率上升(42%vs20%,P<0.05),但胚胎的发育能力下降。这证明HX维持小鼠卵母细胞减数分裂阻滞的作用具有时效性和可逆性的特点,为建立提高体外成熟卵母细胞的发育能力的培养体系打下了基础。

Maintenance of meiotic arrest in mouse oocytes in vitro by hypoxanthine:the time-dependence and reversibility

The developmental competence of in vitro matured oocytes is generally lower than that of the in vivo matured. Hypoxanthine, a physiological meiosis inhibitor in the follicular fluid, was used to inhibit nuclear maturation to improve the quality of oocytes matured in vitro. The results are summarized as follows: (1) HX (4 mmol/L) inhibited the meiotic maturation of mouse oocytes efficiently, but GV% decreased as time went by. (2) Maturation of oocytes was not affected when the HX exposure time was less than 24 h, but maturation rate decreased significantly after 24 h of HX inhibition. (3) The cumulus did not expand in medium containing HX, but the ability of cumulus expansion was recovered when returned to maturational medium, if exposure time to HX was less than 6h. (4) The activation rate increased significantly after treatment with HX for 6 h (42% vs. 20%), but no embryo developed to morulae stage. These results indicated that the hypoxanthine could maintain the meiotic arrest of mouse oocytes time-dependently and reversibly.