title: Comparative maturation of cynomolgus monkey oocytes in vivo and in vitro.
abstract: BACKGROUND
  In vitro maturation (IVM) of oocytes followed by fertilization in vitro (IVF) and embryo transfer offers an alternative to conventional IVF treatment that minimises drug administration and avoids ovarian hyperstimulation. However, the technique is less efficient than maturation in vivo. In the present study, a non-human primate model was used to address the hypothesis that the number of oocytes is increased and their nuclear and cytoplasmic maturity after IVM are improved when maturation is initiated in vivo by priming with hCG.
  
  
  METHODS
  Young, adult cynomolgus monkeys were given recombinant human (rh) gonadotropins to stimulate the development of multiple follicles, and oocytes were aspirated 0, 12, 24, or 36 h after injection of an ovulatory dose of rhCG. The nuclear status of oocytes was determined at the time of recovery and after culture for a total elapsed time of 40-44 hours after hCG.
  
  
  RESULTS
  Priming with hCG significantly increased the number of oocytes harvested, especially after delaying aspiration for 24 h or longer. Nuclear maturation after the full period in culture was also enhanced by priming: 71.5, 83.6, and 94.6% of oocytes collected at 0, 12, and 24 h hCG had progressed to MII by the end of the culture period, compared to 87.8% of oocytes that were retrieved at 36 h. A large proportion of oocytes reaching the MII stage had either or both abnormal spindles (>40%) and misaligned chromosomes (>60%), judging by immunofluorescence microscopy, but these abnormalities were independent of culture time. The mitochondria were evenly distributed throughout the cytoplasm at all stages of maturation. Importantly, there was no microscopic evidence that the duration of culture had any injurious effects on the cells.
  
  
  CONCLUSIONS
  In conclusion, the evidence supports this non-human primate as a model for human IVM and the practice of priming with hCG to promote developmental potential.
authors.affiliation: The Jones Institute for Reproductive Medicine, Department of Obstetrics and Gynaecology Eastern Virginia Medical School, Norfolk, VA 23507, USA. Hay2003@med.cornell.edu
authors.forename: Hang
authors.initials: H
authors.lastname: Yin
authors.forename: Diane M
authors.initials: DM
authors.lastname: Duffy
authors.forename: Roger G
authors.initials: RG
authors.lastname: Gosden
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000648:ultrastructure; D002478:Cells, Cultured / Q000166:cytology; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D008252:Macaca fascicularis / Q000502:physiology*; D008540:Meiosis; D008928:Mitochondria / Q000648:ultrastructure; D023421:Models, Animal; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects; D009866:Oogenesis / Q000187:drug effects; D010062:Ovulation Induction; D011994:Recombinant Proteins / Q000494:pharmacology; D008941:Spindle Apparatus / Q000648:ultrastructure; D013997:Time Factors; D020858:Tissue and Organ Harvesting / Q000379:methods
chemical_list: D006063:Chorionic Gonadotropin; D011994:Recombinant Proteins