In vitro growth and maturation as well as fertilization of mouse preantral oocytes from vitrified ovaries

Objective: To examine the capacity for fertilization and development of preantral oocytes in oocyte-granulosa cell complexes (OGC) originating from vitrified ovaries. Design: Experimental animal study. Setting:University-based research laboratory. Animal(s): Normal (C57BL/6xDBA2) F1 mice in a laboratory environment. Intervention(s): Vitrification of mouse ovaries using polyester sheets as a storage device; collection of OGC by enzymatic treatment; in vitro growth (IVG), in vitro maturation (IVM), and in vitro fertilization (IVF). Main Outcome Measure(s): We performed histologic analysis of vitrified and warmed ovaries, and measured the successful rate in IVG, IVM, and IVF of oocytes in the OGC collected from the ovaries. Result(s): The cortical region of ovaries maintained good morphologic structure after vitrification and warming. Upon IVG and IVM, 75.9% of oocytes in OGC matured to the metaphase II (MII) stage. The fertilization rate of these oocytes was 57.5% as compared with 69.5% for fresh ovaries. Conclusion(s): The vitrification method used was effective for storage of ovaries. The oocytes enclosed in preantral follicles from the ovaries preserved capacity for fertilization and development to preimplantation embryos. ((C) 2004 by American Society for Reproductive Medicine.)