Figure 2. IGF2 administration in culture medium improves the oocytes maturation and early embryonic developmental competence of aged mice. (A) Schematic diagram showing IGF2-treatment of oocytes and early embryos in M16 medium in vitro. (B, C) Quantitative analysis of GVBD (B) and Pb1 extrusion in control oocytes (n = 164) and IGF2-treated oocytes (n = 180) (C). (D) Quantitative analysis of blastocysts in control embryos (n = 218) and IGF2-treated embryos (n = 222). (E) Morphology of in vitro cultured oocytes and embryos examined for development within specific time frames. Arrows indicate the oocytes which failed to extrude a polar body; arrowheads denote embryos which failed to develop into blastocysts. Scale bar, 100 μm. (F) Quantitative analysis of the pregnancy rate in the control and IGF2-treated embryos. 15 blastocysts were transferred into the uterus of each female. n here indicates the numbers of females used as recipients. *p < 0.05. A Student’s t-test (two-tailed). NS, not significant.