Whether for the prepubertal or pubertal child, the goal of fertility preservation is to obtain cells or tissues to be used to produce future children. For the prepubertal child, preservation efforts involve germ cells, earlier forms of sperm, and immature follicles, rather than mature spermatozoa or follicles. Options for prepubertal children include for boys freezing testicular tissue and extracting testicular sperm or for girls obtaining ovarian cortical or follicular tissue for storage. These procedures involve extraction and storage of immature gametes for subsequent in vitro maturation, although attempts for sperm currently involve only animal studies. For adolescent subjects who have sufficient gonadal development and reserve, sperm, oocytes, and ovarian cortex can be retrieved as among adults.