Modlinski J A, Smorag Z
Department of Embryology, University of Warsaw, Poland.
Mol Reprod Dev. 1991 Apr;28(4):361-72. doi: 10.1002/mrd.1080280409.
The development of nuclear-transfer oocytes and zygotes was tested in the rabbit. Metaphase II oocytes and zygotes in the early pronuclear stage were treated with a cytoskeletal inhibitor (cytochalasin D), enucleated, and subsequently fused either with single blastomeres from eight- and 16-cell stages (oocytes and zygotes) or with pronuclei-containing karyoplasts (zygotes only). Also, nonenucleated zygotes were fused with 1/8 blastomeres. Fusion was performed by means of an electric field. Development of reconstituted embryos was monitored mainly in vitro, but a certain number of embryos developed from oocytes and zygotes receiving nuclei from eight-cell stages were also transferred into pseudopregnant does. Development of nuclear-transfer oocytes was distinctly better than that of nuclear-transfer zygotes, since 16.9% and 9.5% oocytes vs. 8.1% and 3.7% zygotes carrying eight- and 16-cell nuclei, respectively, developed to the blastocyst stage. Two advanced but already dead fetuses were found after transfer of 27 four-cell embryos obtained after fusion of oocytes with 1/8 blastomeres. No implantations were observed after transfer of 25 four-cell embryos developed from enucleated zygotes receiving eight-cell nuclei. These findings indicate that, in the rabbit, some nuclei from 16-cell embryos are still capable of promoting at least preimplantation development. Comparison between the developmental abilities of oocyte- and zygote-derived nuclear-transfer embryos also suggests that the cytoplasmic environment of recipient cell is more crucial for the development of reconstituted embryos than the stage of introduced nuclei (at least up to the 16-cell stage). The majority of pronuclear exchange embryos (69.9%) and 40% of nonenucleated zygotes receiving eight-cell nuclei were able to develop to the blastocyst stage. This latter observation indicates, similarly as with mouse, a supporting role of residual pronuclei for participation of an eight-cell nucleus in the development of reconstituted zygotes.
在兔体内对核移植卵母细胞和受精卵的发育情况进行了检测。用细胞骨架抑制剂（细胞松弛素D）处理处于中期II的卵母细胞和原核早期的受精卵，进行去核操作，随后将其分别与来自8细胞期和16细胞期的单个卵裂球（卵母细胞和受精卵）或含原核的核质体（仅针对受精卵）融合。此外，未去核的受精卵与1/8卵裂球进行融合。融合通过电场进行。主要在体外监测重构胚胎的发育情况，但也将一定数量由接受8细胞期细胞核的卵母细胞和受精卵发育而来的胚胎移植到假孕母兔体内。核移植卵母细胞的发育明显优于核移植受精卵，因为携带8细胞期和16细胞期细胞核的卵母细胞分别有16.9%和9.5%发育到囊胚期，而受精卵分别只有8.1%和3.7%发育到囊胚期。在将卵母细胞与1/8卵裂球融合后获得的27个4细胞胚胎进行移植后，发现了2个发育较成熟但已死亡的胎儿。在将接受8细胞期细胞核的去核受精卵发育而来的25个4细胞胚胎进行移植后，未观察到着床现象。这些发现表明，在兔体内，16细胞胚胎的一些细胞核仍能够促进至少着床前的发育。卵母细胞来源和受精卵来源的核移植胚胎发育能力的比较还表明，受体细胞的细胞质环境对重构胚胎的发育比导入细胞核的阶段（至少到16细胞期）更为关键。大多数原核交换胚胎（69.9%）和40%接受8细胞期细胞核的未去核受精卵能够发育到囊胚期。后一观察结果表明，与小鼠情况类似，残留原核对8细胞期细胞核参与重构受精卵的发育起到支持作用。
