Preliminary experience with human oocyte cryopreservation using 1,2-propanediol and sucrose

Feasibility of cryopreservation of mature human oocytes using 1, 2-propanediol and sucrose was studied initially utilizing 1 and 2 day old unfertilized oocytes. Of these 285 aged oocytes 55% survived thawing, and 41% of 128 oocytes inseminated by single sperm intracytoplasmic injection (ICSI) fertilized normally. Limited embryonic development occurred in 51% of these embryos (n = 27) observed for the next 4 days. Cryosurvival of fresh donated oocytes (n = 81) was poorer (n = 20; 24.7%), while fertilization (n = 13; 65%) and embryo development (100%) was good prior to uterine transfer on day 3. Eight oocyte recipient cycles were undertaken, in which cryopreserved donated oocytes were thawed and inseminated by ICSI. Five of these cycles reached embryo transfer, and three pregnancies were initiated though none went successfully to term. Oocyte cryopreservation will ultimately facilitate oocyte donation procedures; however, cryosurvival of fresh frozen oocytes must be improved to at least the degree observed with aged unfertilized oocytes.