Borsuk E, Tarkowski A K
Department of Embryology, Institute of Zoology, University of Warsaw, Poland.
Gamete Res. 1989 Dec;24(4):471-81. doi: 10.1002/mrd.1120240413.
Our objective was to examine the ability of nucleate and anucleate fragments of artificially activated mouse eggs to transform sperm nucleus into male pronucleus. To this end, zona-free oocytes in metaphase II were activated by ethanol and bisected into halves (one with the spindle, the other anucleate) either within 10 to 20 min (series A) or 3 or 5 hr later (series B). In series A, the fragments were inseminated 3.5, and 8 h after activation, and in series B, 3 and 5 h after activation. Both nucleate and anucleate fragments lose the capability of transforming sperm nucleus into fully formed pronucleus sometime between 3 and 5 h after activation. In 8 h old parthenogenetic fragments, the majority of sperm nuclei remain unchanged or begin decondensation but never reach the stage of an early pronucleus. In over 1/3 of anucleate fragments of this age group, sperm nuclei develop defectively; chromatin decondenses inside the persisting nuclear envelope. In other experimental groups, the incidence of these abnormal sperm nuclei varies between 0 and 10%. In general, the anucleate fragments retain the capability to transform sperm nuclei (fully or partially) longer than their nuclear counterparts. This difference may be accounted for by a different level of substances required for pronuclear growth (extrachromosomal constituents of the germinal vesicle and nuclear lamins): high and constant in the cytoplasm of anucleate egg halves and low and progressively decreasing in the nucleate halves because of their putative uptake by the female pronucleus. However, the cytoplasmic factors responsible for the initial stages of transformation (nuclear envelope breakdown, chromatin decondensation) become eventually inactivated both in the presence and in the absence of a female pronucleus.
我们的目的是研究人工激活的小鼠卵的有核和无核片段将精子核转化为雄原核的能力。为此，用乙醇激活处于减数分裂中期II的无透明带卵母细胞，并在10至20分钟内（A组）或3或5小时后（B组）将其切成两半（一半带有纺锤体，另一半无核）。在A组中，片段在激活后3.5小时和8小时进行授精，在B组中，在激活后3小时和5小时进行授精。有核和无核片段在激活后3至5小时之间的某个时间都失去了将精子核转化为完全形成的原核的能力。在8小时大的孤雌生殖片段中，大多数精子核保持不变或开始解聚，但从未达到早期原核阶段。在这个年龄组超过1/3的无核片段中，精子核发育有缺陷；染色质在持续的核膜内解聚。在其他实验组中，这些异常精子核的发生率在0%至10%之间变化。一般来说，无核片段比有核片段更长时间地保留将精子核（完全或部分）转化的能力。这种差异可能是由于原核生长所需物质的不同水平（生发泡的染色体外成分和核纤层蛋白）：在无核卵半体的细胞质中高且恒定，而在有核卵半体中低且逐渐降低，因为它们可能被雌原核摄取。然而，负责转化初始阶段（核膜破裂、染色质解聚）的细胞质因子最终在有或没有雌原核的情况下都会失活。
