RESUMEN
BACKGROUND: Successful pregnancies from cryopreserved oocytes are rare, but oocyte vitrification holds great promise for women in need of preserving their fertility due to illnesses that require treatments such as chemotherapy or radiation which cause irreversible depletion of ovarian reserve. The technique may also eventually be beneficial to women who wish to delay pregnancy to pursue educational and professional goals. Attempts at oocyte cryopreservation have until recently been quite disappointing due to three main problems: (1) high water content and intracellular ice crystal formation upon freezing and subsequent meiotic spindle damage, (2) zona pellucida hardening during cryopreservation and thus difficulty with subsequent fertilization and (3) the relatively large size of the cell and thus an unfavorable surface-to-volume ratio for equilibrium of solutes. These roadblocks have been gradually overcome by the use of improved cryoprotectants, intracytoplasmic sperm injection for fertilization, and the replacement of sodium in freezing media with an osmolyte. The net effect has been a substantial increase in oocyte survival and viability after cryopreservation. CASE: We report the first live births in Texas using vitrified oocytes. CONCLUSION: Vitrification may serve as a useful tool in the preservation of oocytes for women who wish to delay child bearing for medical or social reasons.