Cortical granules behave differently in mouse oocytes matured under different conditions.
BACKGROUND
To better understand the differences between in vivo (IVO) and in vitro (IVM) matured oocytes, we studied the chronological changes in cortical granule (CG) distribution and nuclear progression during maturation, and the competence of CG release and embryo development of mouse oocytes matured under different conditions.


METHODS
Oocytes matured in vivo or in different culture media were used and CG distribution and release were assessed by fluorescein isothiocyanate-labelled Lens culinaris agglutinin and laser confocal microscopy.


RESULTS
Tempos of nuclear maturation and CG redistribution were slower, and competence for CG exocytosis, cleavage and blastulation were lower in the IVM oocytes than in the IVO oocytes. These parameters also differed among oocytes matured in different culture media. Hypoxanthine (HX, 4 mM) blocked germinal vesicle breakdown (GVBD), postponed CG migration and prevented CG-free domain (CGFD) formation. Cycloheximide (CHX) facilitated both GVBD and CG migration, but inhibited CGFD formation. The presence of serum in maturation media enhanced CG release after aging or activation of oocytes. Maintenance of germinal vesicle intact for some time by a trace amount (0.18 mM) of HX was beneficial to oocyte cytoplasmic maturation.


CONCLUSIONS
CGs behaved differently in mouse oocytes matured under different conditions, and cytoplasmic maturity was not fully achieved in the IVM oocytes.
Liu
Xin-Yong
XY
Laboratory for Animal Reproduction and Embryology, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai-an City 271018, Shandong Province, People's Republic of China.
Mal
Suo-Feng
SF
Miao
De-Qiang
DQ
Liu
Dong-Jun
DJ
Bao
Shorgan
S
Tan
Jing-He
JH
D000373:Agglutinins / Q000737:chemistry*; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D003470:Culture Media / Q000378:metabolism / Q000494:pharmacology; D003513:Cycloheximide / Q000737:chemistry / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism; D018450:Disease Progression; D046149:Embryo Culture Techniques; D005307:Fertilization in Vitro; D016650:Fluorescein-5-isothiocyanate / Q000494:pharmacology; D019271:Hypoxanthine / Q000737:chemistry / Q000494:pharmacology; D027806:Lens Plant; D008540:Meiosis; D051379:Mice; D018613:Microscopy, Confocal; D008957:Models, Genetic; D009865:Oocytes / Q000166:cytology* / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013997:Time Factors; D015044:Zona Pellucida / Q000378:metabolism
D000373:Agglutinins; D003470:Culture Media; D011500:Protein Synthesis Inhibitors; D019271:Hypoxanthine; D003513:Cycloheximide; D016650:Fluorescein-5-isothiocyanate