Influence of age of host and ovaries on tumorigenesis in intrasplenic and intrapancreatic ovarian grafts.

The formation of tumors in intrasplenic ovarian grafts in castrated hosts has been observed re peatedly in rats (1, 10) and mice (2, 7, 8, 9). In all the studies undertaken up to this time both young hosts and donors were used; in fact, autologous grafts have been made in most of the experiments. The theory has been proposed that ovarian tumorigcnesis occurs in the intrasplenic and intrapancreatic grafts in castrated animals because of the existing hormone imbalance due to a decreased systemic level of estrogen and an increased level of gonadotrophin (3, 7). Similar conditions might oc cur in old animals whose ovaries have lost most of their capacity to produce hormones. It is known, for example, that urinary gonadotrophins increase subsequent to the menopause. Under such condi tions, why do not granulosa cell tumors occur more frequently, if the above theory is correct? Two possibilities present themselves: (a) The ovaries of old animals may be refractory to stimulation by even augmented amounts of gonadotrophin or (6) the level of gonadotrophin may be inadequate in quality or quantity. The former assumption seemed more likely, so experiments were designed to investigate this hypothesis.