Development of antral follicles in human cryopreserved ovarian tissue following xenografting

This study reports the first gross morphological and histological evidence of antral follicle development in human ovarian tissue following cryopreser vation, Human ovarian tissue was cryopreserved using propanediol and sucros e and grafted under the renal capsule of bilaterally oophorectomized severe combined immunodeficient (SCID) mice. Follicles at all stages of developme nt were observed in the grafted tissue whereas, prior to grafting, only pri mary and primordial follicles were present. Antral follicles were rarely ob served on grafts examined <20 weeks after grafting either non-frozen tissue (fresh, 1/7) or cryopreserved tissue (0/11), In contrast, development of a t least one antral follicle was evident on the majority of sites <greater t han or equal to>20 weeks after grafting (fresh 7/9, cryopreserved 18/24), A ntral follicle diameters ranged from 0.1 to 5.0 mm. Histological examinatio n of these antral follicles indicated normal follicular morphology, i.e, an tral cavities encapsulated by concentric layers of theca and granulosa cell s. Pedicles containing germinal vesicle oocytes were observed protruding fr om the granulosa cell layers. The development and morphology of the cryopre served and fresh tissue following grafting was similar.