Laboratory methods Cryopreservation of ovarian fragments will use a vitrification protocol similar to earlier report for oocyte cryo-storage (Yoon et al. 2003). Because the cryo-preservation reagents can easily penetrate primordial follicles as compared with the large oocytes, we anticipate efficient preservation of these follicles. In young patients, one 1 mm cortical cubes contains ~50 primordial follicles.