ISOLATION AND CHARACTERIZATION OF PRIMORDIAL FOLLICLES FROM FRESH ANDCRYOPRESERVED HUMAN OVARIAN TISSUE

Objective: To develop an efficient isolation technique for human primo rdial follicles. Design: Prospective, experimental study of ovarian bi opsies collected from healthy women undergoing elective cesarean secti on. Ovarian blocks either were fixed for histology and follicle counti ng or partially disaggregated with type 1A collagenase before or after cryopreservation. After partial disaggregation, follicles were isolat ed by microdissection. Setting: Leeds General Infirmary. Main Outcome Measure(s): Follicle viability was assessed with live-dead stains usin g 5- (and 6-) carboxyfluorescein diacetate, succinimidyl ester and pro pidium iodide, respectively, and using electron microscopy. The number s recovered were expressed as a percentage of the numbers of primordia l follicles in comparable blocks of tissue and the viability of the wh ole follicle and oocyte were scored separately. Result(s): On average, 18.0 +/- 3.8 and 15.9 +/- 2.2 (mean +/- SEM) follicles per block were recovered from fresh and cryopreserved ovarian tissue, respectively, corresponding to recovery rates of 57.9% +/- 8.8% and 56.2% +/- 16.7%. In the fresh group, the percent viability of whole follicles and oocy tes were 71.6% +/- 2.4% and 91.3% +/- 2% compared with 71.5% +/- 4.7% and 95% +/- 4.3% in the frozen-thawed group. Electron microscopy confi rmed that the majority of the cells lacked ultrastructural signs of da mage after isolation and cryopreservation. Conclusion(s): Primordial f ollicles can be isolated from fresh and cryopreserved human ovarian ti ssue with similar high efficiency and viability rates.