Assessment of nuclear and cytoplasmic maturation in in-vitro matured human oocytes.
BACKGROUND
With improved prospects for the use of human oocyte in-vitro maturation in assisted reproductive technologies, the need to define more clearly the coordination of nuclear and cytoplasmic maturation has arisen.


METHODS
Immunofluorescence and confocal microscopy were used to evaluate cell cycle-dependent modifications in chromatin and microtubules in human germinal vesicle oocytes (n = 455) undergoing in-vitro maturation.


RESULTS
Four distinct classes of germinal vesicle stage oocytes were identified based on the expression of G2/interphase characteristics, but, of these, only one class of oocytes was competent to complete meiotic progression to metaphase-II in vitro. The majority of germinal vesicle stage oocytes resumed meiosis within 6 h (88.9%) of culture and exhibited an accelerated pace of progression to metaphase-II (66.7%) over 24 h, but in general were unable to maintain meiotic arrest and defaulted into interphase within 24 h of polar body emission. Characterization of microtubule dynamics and chromatin phosphorylation demonstrates specific cell cycle deficiencies in in-vitro matured human oocytes.


CONCLUSIONS
This work forms a basis for future studies aimed at optimizing nuclear and cytoplasmic maturation during in-vitro maturation.
Combelles
C M H
CM
Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA 02111, USA.
Cekleniak
N A
NA
Racowsky
C
C
Albertini
D F
DF
D015415:Biomarkers; D002467:Cell Nucleus / Q000502:physiology*; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000502:physiology; D002843:Chromatin / Q000648:ultrastructure; D003593:Cytoplasm / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008540:Meiosis / Q000502:physiology; D008870:Microtubules / Q000502:physiology; D009865:Oocytes / Q000502:physiology*
D015415:Biomarkers; D002843:Chromatin