Effects of cyclic increase in gonadotropins on the in vitro development of primordial follicles to antral stage.

The aim of this study was to evaluate the effects of FSH and LH on follicle development during a long-term culture of cryopreserved human ovarian tissue, using morphological and ultrastructural examinations. Thawed ovarian tissue slices from a 4-year-old child with Wilms tumor were cultured for 32 weeks in two different culture conditions, without (medium A) and with (medium B) a monthly peaked increase in FSH and LH. At week 32, in the medium B cultured tissue, a cluster of preantral follicles associated with two oocytes prematurely ovulated was observed, suggesting that the cyclic increase of gonadotropins promoted thawed follicles to grow up to the antral stage. However, the integrity and coordinated follicle development were not maintained. Indeed, ultrastructural analysis showed a well-preserved "naked" oocyte with concomitant features of immaturity and maturity, as if this culture condition had led to an asynchronous maturation of oocyte cytoplasmic components.