Yokoo Masaki, Sato Eimei
Laboratory of Animal Reproduction, Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
Int Rev Cytol. 2004;235:251-91. doi: 10.1016/S0074-7696(04)35006-0.
In most mammals, the oocyte in the Graafian follicle is surrounded by tightly packed layers of cumulus cells, forming the cumulus-oocyte complex. During the preovulatory period, cumulus cells change from a compact cell mass into a dispersed structure of cells for the synthesis and deposition of a mucoid intercellular matrix, a process referred to as cumulus expansion. Cumulus expansion is thought to influence a variety of fundamental developmental changes during oocyte maturation. Volumetric expansion of the cumulus-oocyte complex correlates, at least in pig, with the outcome of oocyte maturation, fertilization, and embryo development. Therefore, detailed functional studies of cumulus expansion seem to be required to elucidate the mechanism of oocyte maturation. We summarize the current knowledge about (1) morphological changes of cumulus-oocyte complexes during oocyte maturation, (2) follicle factors inducing cumulus expansion, (3) the role of cumulus expansion in oocyte maturation, (4) cytoplasmic regulators of oocyte maturation, and (5) possible roles of cumulus expansion.
在大多数哺乳动物中，格拉夫卵泡中的卵母细胞被紧密排列的卵丘细胞层所包围，形成卵丘-卵母细胞复合体。在排卵前期，卵丘细胞从紧密的细胞团转变为分散的细胞结构，用于合成和沉积黏液样细胞间基质，这一过程称为卵丘扩展。卵丘扩展被认为会影响卵母细胞成熟过程中的各种基本发育变化。卵丘-卵母细胞复合体的体积扩展至少在猪中与卵母细胞成熟、受精和胚胎发育的结果相关。因此，似乎需要对卵丘扩展进行详细的功能研究，以阐明卵母细胞成熟的机制。我们总结了目前关于（1）卵母细胞成熟过程中卵丘-卵母细胞复合体的形态变化，（2）诱导卵丘扩展的卵泡因子，（3）卵丘扩展在卵母细胞成熟中的作用，（4）卵母细胞成熟的细胞质调节因子，以及（5）卵丘扩展的可能作用的知识。
