This study was conducted to examine the influences of two human chorion gonadotrophins (hCGs) being injected into young or aged (45- to 65-week old) outbred (ICR) mice on developmental capacity of oocytes retrieved. In vitro-culture and parthenogenetic activation of oocytes retrieved were employed for the assessment. Superovulation was determined as being induced when more than 25 oocytes were retrieved. No aged mice were superovulated, while in contrast, 67-100% were superovulated in the 6- to 8-week-old (young) mice. In the aged, hCG injection yielded better retrieval (5 vs. 13 to 14.8 oocytes/mouse). Overall, no significant difference between two hCGs was detected but between the young and aged, significant differences in maturational arrest (0% vs. 39% MI arrest and 46% vs. 15% degeneration) and developmental capacity (24% vs. 46% 8-cell embryo development) were detected. In conclusion, hCG injection contributes to increasing oocyte retrieval from aged outbred mice, but the kinds of gonadotrophin influenced the efficiency of hyperstimulation induction in specific ages.

Abstract
 INTRODUCTION
 MATERIALS AND METHODS
  Experimental animals
  Collection of mature oocytes
  Parthenogenetic activation and IVF of oocytes
  Statistical analysis
 RESULTS
 DISCUSSION
 REFERENCES

• Myungook Lee(Department of Agricultural Biotechnology, Seoul National University)
• Hyosook Kwun(Department of Agricultural Biotechnology, Seoul National University)
• Jong Il Ahn(Research Institutes of Agriculture and Life Sciences, Seoul National University)
• Dong Woo Ko(Department of Agricultural Biotechnology, Seoul National University)
• Jiyeon Ahn(Department of Agricultural Biotechnology, Seoul National University)
• Jeong Mook Lim(Department of Agricultural Biotechnology, Seoul National University, Research Institutes of Agriculture and Life Sciences, Seoul National University) Correspondence