Development of mouse oocytes superovulated at different ages

The development of oocytes superovulated at 25, 50, or 90 days in four mouse strains (C57BL/6N, DBA/2N, ICR, and B6D2F1) was examined using the techniques of in vitro fertilization, culture, and transfer of two-cell embryos to pseudopregnant recipients. The highest number of ova were obtained from superovulated 25-day-old mice in all strains. Approximately 80% of oocytes developed to the two-cell stage after in vitro fertilization. Of these living oocytes, 60% developed to weanling stage through the recipient. These results suggested that donor age among 25, 50, or 90-day-old mice has no influence on the viability of superovulated oocytes. Consequently, we conclude that superovulated 25-day-old mice offer an economical and efficient source of viable oocytes for the production of transgenic mice.