Freezing of human ovarian tissue - not the oocytes but the granulosa is the problem

The freezing of human ovarian tissue may be the key for restoring fertility after systemic therapy of cancer. In contrast to others we investigated th e survival rate of whole follicles, and had a special look at the granulosa cells. Ovarian tissue was collected laparoscopically (n = 10) and divided into equal parts for freezing (n = 1570) or as control (n = 1660). The cryo preservation was done slowly, or as a ultrarapid freezing. After thawing th e number of follicles, oocytes and granulosa cells surviving was counted an d corrected for equal volumina of the samples. While 84.5% of the oocytes s urvived freezing, only 40.4% of the follicles were intact after thawing. Th e data show that the procedure damaged follicles, which mainly affected the granulosa cells. As the intactness of follicles may play a critical role f or the maturation of the oocytes after thawing the protocols should be opti mised to meet the needs of oocytes and granulosa cells. (C) 2000 Elsevier S cience Ireland Ltd. All rights reserved.