Autonomous Transplantable Pituitary Tumors Arising in Growths Dependent on Absence of the Thyroid Gland. ∗

Summary

1. All of 7 pituitary growths induced by thyroid destructive doses of I131 proved transplantable to mice similarly pre-treated but not to normal mice. In a sub-passage of one strain (B3) a tumor acquired the ability to grow in normal mice giving origin to a pituitary tumor line which can be grafted as readily if not better in normal mice than in radio-thyroidectomized mice. 2. In normal hosts of this autonomous tumor there is a tremendous hyperplasia of the thyroid gland with multiple adenoma-like nodules. There is also some gonadal stimulation of the hosts but no evidence of ACTH secretion by these tumors. Thus a gain in autonomy occurred with retention of the ability of these pituitary tumor cells to secrete thyroid and gonad stimulating hormones. 3. These studies indicate the uncertainty and relativity of the term “autonomy” in relation to neoplastic growth. Regional metastases do not indicate “autonomy” as they occur also with conditioned neoplasms.