Goudet G, Bézard J, Belin F, Duchamp G, Palmer E, Gérard N
Institut National de al Recerche Agronomique-Haras Nationaux, Equipe de Reproduction Equine, P.R.M.D., F-37380 Nouzilly, France.
Biol Reprod. 1998 Aug;59(2):456-62. doi: 10.1095/biolreprod59.2.456.
The in vitro maturation rate of equine oocytes remains low, regardless of culture conditions. Our objective was to determine the reasons for failure of equine oocytes to resume meiosis during in vitro maturation and to ascertain the influence of the estrous cycle stage on meiotic competence. In 10 cyclic mares, 7 ultrasound-guided follicular punctures were performed alternately during the follicular phase (group DF; n = 3 punctures), at the end of the follicular phase (group EF; n = 2), and during the luteal phase (group DL; n = 2). We evaluated the competence of the oocytes for in vitro maturation and measured their maturation-promoting factor activity by histone H1 kinase assay. Puncturing once at the end of the follicular phase and once during the luteal phase, or three times during the follicular phase, yielded about 11 cumulus-oocyte complexes per 22 days. The maturation rate was different between the groups, 51% in group EF, 34% in group DL (p < 0.05), and 15% in group DF (p < 0.01), and it increased with an increase in follicular diameter (p < 0.05). After in vitro culture, the H1 kinase activity was lower in oocytes that remained in germinal vesicle or dense chromatin stages than in oocytes that reached metaphase I or metaphase II (p < 0.05). The H1 kinase activity was not different between oocytes in germinal vesicle stage after in vitro maturation and immature oocytes that were not cultured in vitro, and was higher in preovulatory oocytes that reached metaphase II in vivo than in the oocytes that reached metaphase II after in vitro maturation (p < 0.001). This is the first report on kinase activity in the equine oocyte.
无论培养条件如何，马卵母细胞的体外成熟率仍然很低。我们的目的是确定马卵母细胞在体外成熟过程中减数分裂恢复失败的原因，并确定发情周期阶段对减数分裂能力的影响。在10匹处于发情周期的母马中，在卵泡期（DF组；n = 3次穿刺）、卵泡期末期（EF组；n = 2次）和黄体期（DL组；n = 2次）交替进行7次超声引导下的卵泡穿刺。我们评估了卵母细胞的体外成熟能力，并通过组蛋白H1激酶测定法测量了它们的成熟促进因子活性。在卵泡期末期穿刺一次和在黄体期穿刺一次，或者在卵泡期穿刺三次，每22天可获得约11个卵丘-卵母细胞复合体。各组之间的成熟率不同，EF组为51%，DL组为34%（p < 0.05），DF组为15%（p < 0.01），并且随着卵泡直径的增加而增加（p < 0.05）。体外培养后，处于生发泡或致密染色质阶段的卵母细胞的H1激酶活性低于达到中期I或中期II的卵母细胞（p < 0.05）。体外成熟后生发泡期的卵母细胞与未进行体外培养的未成熟卵母细胞之间的H1激酶活性没有差异，并且体内达到中期II的排卵前卵母细胞的H1激酶活性高于体外成熟后达到中期II的卵母细胞（p < 0.001）。这是关于马卵母细胞激酶活性的首次报道。
