胚层的

An embryo at the stage following the blastula, consisting of a hollow, two-layered sac of ectoderm and endoderm surrounding an archenteron that communicates with the exterior through the blastopore.

原肠胚一种囊胚之后的胚胎，含有中空、两层的外胚层和内胚层，包围着通过胚孔跟外界交流的原肠

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastocysts followed by fusion of cytoplasm and nucleus and cleavage in vitro. During the fusion of cytoplasm, the DNA methylation levels of the fused embryos are as high as these of two-cell diploid embryos in vivo Then the embryos are rapidly demethylated when the nucleus begin to fuse, resulting in the lowest DNA methylation levels when the nucleus are fused completely. After that, the DNA methylation levels of the fused embryos are gradually increased until the morula stage. However, whereas an asymmetric distribution of DNA methylation is established in vivo-derived blastocysts with a higher methylation level in the inner cell mass than that in the trophectoderm, we can not detect the asymmetric distribution in most in vitro-derived tetraploid blastocysts.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在桑葚胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastocysts followed by fusion of cyto-plasm and nucleus and cleavage in vitro. During the fusion of cytoplasm, the DNA methylation levels of the fused embryos are as high as these of two-cell diploid embryos in vivo Then the embryos are rapidly demethylated when the nucleus begin to fuse, resulting in the lowest DNA methylation levels when the nucleus are fused completely. After that, the DNA methy-lation levels of the fused embryos are gradually increased until the morula stage. However, whereas an asymmetric distribu-tion of DNA methylation is established in vivo-derived blastocysts with a higher methylation level in the inner cell mass than that in the trophectoderm, we can not detect the asymmetric distribution in most in vitro-derived tetraploid blastocysts.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在桑葚胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

Tetraploid embryos could be produced by electrofusion at the stage of two-cell embryos, which could develop to blastcysts fellowed by fusion of cytoplasm and nucleus and cleavage in vitro.After fusion of cytoplasm, the DNA methylation levels of the fused embryos was very high as well as two-cell diploid embryos in vivo.Then the embryos was rapiddly demethylated when the nucleus begin to fuse, resulting the lowest DNA methylation levels when the nucleus fused completely.After that, the DNA methylation levels of fused embryos were gradually increased until the blastocysts stage.However, whereas an asymmetric distribution of DNA methylation was established in an vivo-derived blastocysts with a higher methylation level in the inner cell mass than in the trophectoderm, in most vitro-derived tetraploid blastocysts, we can not detect the asymmetric distribution.

结果表明：利用电融合方法制备的小鼠四倍体胚胎在体外培养体系中经历细胞质融合、细胞核融合及细胞继续分裂发育直到囊胚期的过程，在细胞质融合的时候胚胎卵裂球同体内体外培养二倍体胚胎一样，呈现高度甲基化状态；在细胞核开始融合的时候，甲基化水平急速下降，在细胞核完全融合的时候甲基化水平达到最低点；随着胚胎继续分裂，胚胎甲基化水平逐渐增加，在囊胚期甲基化水平最高；但是囊胚期四倍体胚胎内细胞团同滋养层细胞甲基化荧光信号没有差别，这与体内体外培养二倍体囊胚内细胞团细胞甲基化荧光强度高于滋养层细胞甲基化荧光强度不同。

In vitro, ES cells can spontaneously differentiate into embryoid bodies containing derivatives of three germ layers.

在体外，ES细胞可自发分化为含有内胚层、中胚层、外胚层来源的多种组织和细胞的拟胚体。

The embryonic vessels failed to invade into the labyrinthine layer of placenta, which impaired the embryonic-maternal vascular connection. These defects could not be rescued by wild-type tetraploid blastocysts, excluding the possibility that they were due to the extraembryonic tissues.

组织免疫组化分析结果显示：毛细血管腔异常扩张，排列紊乱，不能形成大血管及细致有序的血管网络；胚外中胚层来源的卵黄囊脏层扁平上皮细胞形态变圆，与内皮细胞连接受损；胚胎血管不能侵入胎盘迷路层，胚体与母体血管连接受损。

The results were:1The mean somatotypes in male 2.2\_4.5\_2.4 and female 4.3\_4.2\_1.5 are balanced mesomorph and endomorph-mesomorph,respectively.2Very significant sexual difference is found in adult's of Dong nationality(P.001) while SAD and T are 2.33 and 11.9 respectively.3Compared with the data home and abroad,the somat...

结果表明：1 侗族成人男女的平均体型值分别为 2 2— 4 5— 2 4和 4 3— 4 2— 1 5 ，侗族成人男女分别属均衡的中胚层体型和内胚层—中胚层均衡体型；2 侗族成人男女间SAD值为 2 33，T为 1 1 9，男女间的体型有非常显著性差异(P 0 0 1 )；3与国内、外资料相比，侗族男女的内、中因子值和男性外因子值居中，女性外因子值最低

Results the male value of somatotype was (2.9-3.9-3.5) and female was (4.9-1.4-3.2), they were balanced mesomorphy and endomorphy-mesomorphy respectively.

结果 男女青年平均体型值分别为（2.9-3.9-3.5）和（4.9-1.4-3.2），男女青年分别属均衡的中胚层体型和内胚层-中胚层均衡体型；男女青年间sad值为2.73，体型有非常显著的性别差异(p＜0.001)。

The 28S rDNA molecular phylogenetic trees showed: 1 entoprocts and phylactolaemate ectoprocts constituted a sister group, strenghthening the opinion that entoprocts should be reunited into phylum Bryozoa; 2 the cheilostome gymnolaemates was obviously non-monophyletic; 3 bryozoans itself was polyphyletic beyond any doubt, its main lineages were scattered in different positions of the lophotrochozoan trees; 4 to our great interests, the phylogenetic position of cheilostomes was between the diploblastic and the triploblastic, indicating they may play an important role during the evolution route from the diplobastic to the triploblastic animals.

28S rDNA分子系统树显示，内肛动物和被唇类外肛动物聚在一起并互为姐妹群，支持将内肛动物重新归入苔藓动物门的结论；唇口目裸唇类外肛动物绝非单系发生；苔藓动物本身也不是单系发生的，其主要类群分别位于触手冠担轮动物系统树的不同位置，特别是，唇口目苔藓动物的系统地位介于二胚层动物和其它三胚层动物之间，可能是二胚层动物向三胚层动物演化过程中的一个关键类群。

A variation in gastrulation, involving the movement of cells into endodermal and mesodermal positions through the thickened primitive streak, arose in reptiles and can still be seen in bird and mammalian embryos, lending support

密实的原肠胚通过细胞运动进入内胚层和中胚层，爬虫，鸟，哺乳动物的胚胎都如此。因此提出这样的理论，鸟类和哺乳动物是由爬虫进化而来的。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。