CLINICAL-APPLICATION OF HUMAN EGG CRYOPRESERVATION

Clinical egg cryopreservation has been applied during a 4-year period with some limited success. Mostly mature and a few immature eggs were frozen slowly and thawed rapidly in 1,2-propanediol and sucrose, and s ubsequently inseminated by intracytoplasmic sperm injection (ICSI), Th ree studies were performed in which: (i) it was established that 55% o f aged unfertilized mature eggs survive freezing; (ii) in 22 cycles of thawed donated eggs cryosurvival was 24% with 15 cycles reaching tran sfer, and five pregnancies were initiated, one of which went to term a t 39 weeks with fraternal twin boys, and one remains ongoing at 37 wee ks; and (iii) in five cycles, where in-vitro fertilization patients ha d some of their own eggs frozen/thawed, cryosurvival of mature eggs wa s poor at only 2.2%, although 44% sibling germinal vesicle (GV) stage eggs survived. A normal female infant delivered at 40 weeks arose from transfer of two embryos where GV eggs underwent in-vitro maturation p ost-thaw and were fertilized by ICSI. Pregnancies reported here and by others indicate a burgeoning awareness of the potential benefits of e gg cryopreservation, prompting cautious optimism for the future of thi s technology.