[Fertility preservation for children and adolescents before gonadotoxic treatment].

Gonadotoxic therapies during childhood may impair future fertility in adult life and fertility preservation techniques should be discussed before starting gonadotoxic therapies. In both sexes, fertility preservation means immature gametes cryopreservation. For girls, ovarian tissue cryopreservation is the only existing option to preserve fertility in prepubertal girls at risk of premature ovarian failure. This promising approach involves the storage of a large number of follicles, which could subsequently be transplanted or cultured to obtain mature oocytes. For boys, spermatogonial stem cells can be cryopreserved and testicular pieces can be stored for future use. For prepubertal boys it is still an experimental procedure. Animal data reveals that healthy offspring were obtained after grafting of frozen spermatogonia and after in vitro maturation.