In vitro maturation and fertilization of vitrified immature human oocytes, subsequent vitrification of produced embryos, and embryo transfer after thawing.

OBJECTIVE

To report on the capability of vitrified immature human oocytes to undergo in vitro maturation, fertilization, and embryo development, and to report on the post-thaw survival of vitrified embryos.

DESIGN

Case report.

SETTING

University-based IVF unit.

PATIENT(S): Two women (34 and 36 years old) undergoing IVF therapy.

INTERVENTION(S): Immature oocytes, retrieved after ovarian stimulation, were vitrified. Post-thaw, they underwent in vitro maturation and fertilization by intracytoplasmic sperm injection (ICSI). The produced embryos were vitrified at day 2. In one case, the embryos were thawed and transferred.

MAIN OUTCOME MEASURE(S): Post-thaw survival of vitrified immature oocytes, capability for in vitro maturation, fertilization, embryo development; post-thaw survival of vitrified embryos.

RESULT(S): In the first case, six immature oocytes survived after thawing and matured after in vitro maturation. Five of them underwent ICSI, four fertilized, and three cleaved. The embryos were vitrified for future use. In the second case, two out of three immature oocytes survived after thawing. They were normally fertilized and cleaved, and the embryos were vitrified. Later, the embryos were thawed and transferred to the patient.

CONCLUSION(S): These cases demonstrate that vitrified immature oocytes can undergo post-thaw in vitro maturation and fertilization. The produced embryos are capable to undergo vitrification and thawing.