Nucleocytoplasmic ratio of fully grown germinal vesicle oocytes is essential for mouse meiotic chromosome segregation and alignment, spindle shape and early embryonic development
Authors: Cui, Long-Bo; Huang, Xiu-Ying; Sun, Fang-Zhen
Source: Human Reproduction, Volume 20, Number 10, October 2005 , pp. 2946-2953(8)
Publisher: Oxford University Press
Abstract:BACKGROUND: This study examined the effect of nucleocytoplasmic ratio of fully grown germinal vesicle (GV) oocytes on meiotic chromosome segregation and alignment, spindle shape, Ca2+ oscillations and capacity of early embryonic development in mouse. METHODS: GV oocytes with reduced volume (equal to 1/5 to 4/5 of an intact oocyte) were made by micromanipulation to remove different amounts of cytoplasm, and then matured and fertilized in vitro. RESULTS: When >1/2 of GV oocyte cytoplasm was removed, the time-course of GV breakdown (GVBD) was delayed and oocyte maturation rate decreased significantly. Abnormal chromosome segregation rate increased if >1/2 of the cytoplasm was removed from the oocyte. Length and structure of meiotic spindle and chromosome alignment were also impaired by the reduction of cytoplasmic volume. Once matured in vitro, the oocytes could undergo Sr2+-induced Ca2+ oscillations and form pronuclei in a manner independent of nucleocytoplasmic ratio, but their ability to develop to 2-cell embryos was affected if >1/2 of their cytoplasm was removed from the GV oocytes. CONCLUSIONS: These results suggest that nucleocytoplasmic ratio is essential for normal meiotic chromosome segregation, spindle formation and chromosome alignment over the metaphase spindle, and development to 2-cell stage, for which 1/2 of the volume of the GV oocyte appears to be a threshold.
Document Type: Research Article
Affiliations: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100080 and
Publication date: October 2005
- Human Reproduction features full-length, peer-reviewed papers reporting original research, clinical case histories, as well as opinions and debates on topical issues. Papers published cover the scientific and medical aspects of reproductive physiology and pathology, endocrinology, andrology, gonad function, gametogenesis, fertilization, embryo development, implantation, pregnancy, genetics, genetic diagnosis, oncology, infectious disease, surgery, contraception, infertility treatment, psychology, ethics and social issues. The highest scientific and editorial standard is maintained throughout the journal along with a rapid rate of publication.