Effect of age on development of tumours in the intrasplenic ovarian grafts in ovariectomized rats.

Female rats at the age of 1, 3, and 14-16 months ("young", "adult" and "old" groups respectively) were bilaterally ovariectomized and one of the removed ovaries was autoimplanted into the spleen. The total intrasplenic ovarian tumour incidence was equal in the rats subjected to the operation at 3 and 14-16 months (77.4% and 80.6% respectively) and tumours developed more frequently in rats exposed to surgery at the age of 1 month (94.5%), P < 0.05. The incidence of Sertoli and Leydig cell tumours was increased and their latency was decreased in the old group in comparison to the adult one. In rats exposed to the operation at the age of 3 months, granulosotheca cell tumours developed more frequently than other tumour types, and in the young group thecomas were discovered more often than in both older groups. Dysgerminomas and luteomas were discovered only in intrasplenic grafts of rats of the young group. It is supposed that the differences in structure and proliferative activity of various ovarian tissues between young, adult and old rats at the moment of intrasplenic transplantation, as well as the differences in their response to gonadotropic stimulation play a significant role in the development of ovarian tumours of varied histogenesis in the intrasplenic ovarian grafts.