Ovarian culture with mouse serum improves follicle development compared with fetal bovine serum, showing the importance of as yet unidentified factors in follicle growth.

Context For survivors of childhood blood cancer, fertility preservation through ovarian tissue cryopreservation (OTC) and reimplantation is not recommended because of the risk of reintroducing malignant cells. Since a robust in vitro ovarian tissue culture system does not exist for humans, new approaches are needed. Aims To investigate new approaches to in vitro follicle growth, our aim was to determine whether mouse serum (MS) could support follicle development better in mouse ovaries in vitro compared to fetal bovine serum (FBS). Methods Neonatal ovaries were cultured for 14days in either MS or FBS. Follicle development and health were assessed by histological and molecular analyses. Anti-Müllerian hormone (AMH) and laminin were analysed using immunohistochemistry. Key results MS supported the development of primordial follicles to preantral follicles, whereas those in FBS did not develop beyond primary. Ovaries cultured in MS had fewer atretic follicles than those in FBS. There were more AMH-positive follicles in MS-cultured than in FBS-cultured ovaries, more primary follicles that were AMH-positive and, AMH-positive primary follicles contained more AMH-positive granulosa cells than those cultured in FBS. Finally, ovaries cultured in either MS or FBS contained laminin; however, the follicle basal lamina (FBL) in MS ovaries were more defined. Conclusions MS better supported follicle development, health, and function than did BS, indicating that MS contains additional factors important for follicle development in mice. Implications These findings demonstrated that as-yet-unknown factors exist that are important for in vitro follicle development, and we need to define them, and explore the role of these molecules in human studies.