Fulka J, Motlík J, Fulka J, Crozet N
J Exp Zool. 1985 Aug;235(2):255-9. doi: 10.1002/jez.1402350212.
Porcine ovarian oocytes, isolated from follicles of 5 mm in diameter (large oocytes), were fused either together or with oocytes isolated from follicles of 0.5 mm in diameter (small oocytes). In giant cells composed of two large oocytes (control) germinal vesicle breakdown (GVBD) occurred and two metaphase I chromosome sets (M I) were observed 24 to 30 h after fusion. By contrast, in giant cells composed of one large and one small porcine oocyte, both germinal vesicles (GVs) remained well conserved after 24-30 h of culture. An identical situation was observed after fusion and cultivation of small porcine and large mouse oocytes isolated from preovulatory follicles. The results demonstrate the presence of inhibiting activity in the ooplasm of small porcine oocytes that prevents nuclear maturation of large porcine and mouse oocytes fused to them. This maturation inhibiting activity can be overcome by preincubating large porcine oocytes for more than 14 h before fusion with small oocytes. During preincubation the ooplasm produces sufficient amount of maturation promoting factor (MPF) to overcome the inhibiting activity present in small porcine oocytes thus inducing GVBD and chromatin condensation both in small and large oocytes.
从直径5毫米的卵泡中分离出的猪卵巢卵母细胞（大卵母细胞），要么相互融合，要么与从直径0.5毫米的卵泡中分离出的卵母细胞（小卵母细胞）融合。在由两个大卵母细胞组成的巨细胞（对照）中，融合后24至30小时发生了生发泡破裂（GVBD），并观察到两组中期I染色体（MI）。相比之下，在由一个大的和一个小的猪卵母细胞组成的巨细胞中，培养24 - 30小时后，两个生发泡（GVs）仍保存完好。从排卵前卵泡中分离出的小猪卵母细胞和大的小鼠卵母细胞融合并培养后，观察到相同的情况。结果表明，小猪卵母细胞的卵质中存在抑制活性，可阻止与其融合的大猪和小鼠卵母细胞的核成熟。在与小卵母细胞融合前，将大猪卵母细胞预孵育超过14小时，可克服这种成熟抑制活性。在预孵育期间，卵质产生足够量的成熟促进因子（MPF），以克服小猪卵母细胞中存在的抑制活性，从而诱导小卵母细胞和大卵母细胞中的GVBD和染色质凝聚。
