Development to the blastocyst stage of immature pig oocytes arrested before the metaphase-II stage and fertilized in vitro
Development to the blastocyst stage of immature pig oocytes arrested before the metaphase-II stage and fertilized in vitro
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DOI：
10.1016/j.anireprosci.2005.03.018
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发表时间：
2005-12-01
影响因子：
2.2
通讯作者：
Nagai, T
中科院分区：
文献类型：
--
作者：
Somfai, T;Kikuchi, K;Nagai, T
本研究比较了猪成熟卵母细胞和减数分裂阻滞卵母细胞的体外受精（IVF）和胚胎发育。卵丘-卵母细胞复合体体外成熟48 h后，75.4%的卵丘-卵母细胞复合体排出可见的极体。具有第一极体的卵母细胞（PB+组）大多数处于中期II（M-II）期（91.4%）。大多数没有可见极体的卵母细胞（PB组）似乎停滞在生殖泡（GV）（41.6%）和中期-I（M-I）（34.0%）阶段。卵母细胞体外受精后（IVF第0天），PB+组与PB-组精子穿透率、单精受精率无差异，但穿透后卵母细胞激活率PB+组高于PB-组（P < 0.05）。在第2天，PB+和PB-组中2-4细胞期的胚胎卵裂率无差异（分别为42.1 +/- 48.8%和33.6 +/-2.1%）。在第4天，PB+胚胎发育超过4-细胞期的比率大于PB-胚胎PB+胚胎比PB-胚胎具有更多的细胞（分别为P <0.05、8.3 +/-0.4和6.0 +/-0.8个细胞）。在第6天，PB+胚胎发育到囊胚期的比例大于PB -胚胎（P < 0.05，分别为34.6 +/- 2.4%和20.7 +/-2.8%）。然而，当PB组的GV卵母细胞不包括在重新计算中时，M-I停滞和M-II卵母细胞之间的囊胚率没有差异（分别为35.3%和34.6%）。从PB+组获得的胚胎中的卵裂球核的数目（52.0 ± 2.5）大于从PB-组获得的胚胎中的卵裂球核的数目（29.1 ± 2.8）（P < 0.05）。通过形态学外观确定的囊胚中退化部分的比例在PB+和PB-组中相同。虽然PB+胚胎的质量比PB-组有所提高，但PB+和PB-囊胚中内细胞团和滋养外胚层细胞的比例没有差异（分别为1：1.9和1：2.2）。染色体分析显示，PB+囊胚的二倍体细胞数（69.7%）高于PB-囊胚（44.0%），而PB-囊胚的三倍体细胞数（34.0%）高于PB+卵母细胞（8.4%）。这些结果表明，猪M-II期前停滞的卵母细胞（M-I卵母细胞）在体外成熟培养过程中经历了胞质成熟，体外受精后发育成囊胚的能力与M-II卵母细胞相同，但部分卵母细胞退化或发育延迟，胚胎质量较差。(c)2005 Elsevier B. V.保留所有权利。
In vitro fertilization (IVF) and embryonic development of mature and meiotically arrested porcine oocytes were compared in the present study. After in vitro maturation (IVM) of cumulus-oocyte complexes for 48 h, 75.4% of them extruded a visible polar body (PB). Most of the oocytes with a first polar body (PB+ group) were at the metaphase-II (M-II) stage (91.4%). Most of the oocytes without a visible polar body (PB- group) appeared to be arrested at the germinal vesicle (GV) (41.6%) and metaphase-I (M-I) (34.0%) stages. After IVF of oocytes (day of IVF = Day 0), there was no difference between PB+ and PB- groups in rates of sperm penetration, mono-spermy, however oocyte activation rate after penetration was greater in the PB+ than in the PB- group (P < 0.05). On Day 2, there was no difference between rates of embryos cleaved at the 2-4 cell stages in PB+ and PB- groups (42.1 +/- 48.8% and 33.6 +/- 2.1%, respectively). On Day 4, the rate of PB+ embryos developing beyond the 4-cell stage was greater than that of PB- embryos (P < 0.05, 31.7 +/- 3.9% and 14.1 +/- 1.5%, respectively), and PB+ embryos had more cells than the PB- embryos (P < 0.05, 8.3 +/- 0.4 and 6.0 +/- 0.8 cells, respectively). On Day 6, a greater proportion of PB+ embryos developed to the blastocyst stage than did PB - embryos (P < 0.05, 34.6 +/- 2.4% and 20.7 +/- 2.8%, respectively). However, when the GV oocytes of the PB- group were not included in recalculations, there was no difference in blastocyst rates between M-I arrested and M-II oocytes (35.3 and 34.6%, respectively). The number of blastomere nuclei in embryos obtained from the PB+ group (52.0 +/- 2.5) was greater than that from the PB- group (P < 0.05, 29.1 +/- 2.8). The proportion of degenerated parts in the blastocysts, as determined by morphological appearance, was the same in the PB+ and PB- groups. Although the quality of PB+ embryos was enhanced as compared with that of the PB- group, the proportion of inner cell mass and trophectoderm cells in PB+ and PB- blastocysts did not differ (1: 1.9 and 1:2.2, respectively). Chromosome analysis revealed that PB+ blastocysts had more diploidy (P < 0.05, 69.7%) than did PB- blastocysts (44.0%), whereas PB- blastocysts had more triploid cells (P < 0.05, 34.0%) than did PB+ oocytes (8.4%). These results indicate that pig oocytes arrested before the M-II stage (M-I oocytes) undergo cytoplasmic maturation during maturation culture and have the same ability to develop to blastocysts after IVF as M-II oocytes, but some of them resulted in degeneration or delayed development with poor embryo quality. (c) 2005 Elsevier B.V. All rights reserved.