REGULAR ARTICLES

Cell Research (1996)6:167-175
© 1996 SIBS, CAS All rights reserved 1001-0602/96

The fertilization-indeced Ca2+ oscillation in mouse oocytes is cytoplasmic maturation dependent

Laboratory Molecular Developmental Biology ,Institute of Developmental Biology, Chinese Academy of Sciences, Beijing ,100080, China

Correspondence:

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Abstract

Mature eggs( at metaphase II stage)produce a series of Ca2+ oscillation at fertilization . To define whether the fertilization –induced Ca2+ oscillation os restrict to the metaphase II eggs and cell cycle dependent, mouse oocytes at prophase I (arrested at germinal vesicle stage), metaphase I ,metaphase II , as well as the pronuclear embryos at interphase of the first mitotic division derived from dertiliation or parthenogenetic activation were inseminated after removal of zona pellucida. The results show that the fertilization –induced Ca2+ oscillationis not specific to metaphase II eggs. This is supported by the fact that immature oocytes generated the Ca2+ oscillation at fertilization regardless of their nuclear nuclear progression from prophase I to metaphase I (in vitro matured) stage . More interestingly, it was first found that pronuclear embryos at interphase derived from parthenogenetic activation showed Ca2+ oscillation in response to fertilization while the zygotes at interphase did not after reinsemination or intracytoplasmic at interphase did not after reinsemination or intracytoplasmic injection of sperm extracts which induce Ca2+ oscillation in MII eggs. This suggests that the ability of oocytes to generate Ca2+ oscillation in response to sperm penetration is not regulated in a cell cycle dependent manner but dependent on the cypoplasmic maturation.

Keywords : Fertilization-induced Ca2+ oscillation, mouse oocyte, pronuclear embryo, parthenogenetic activation, cell cycle.