Functional Auto- and Homoplastic Thyroid Grafts in the Rat. ∗

Many of the attempts to graft the thyroid gland have met with little success. Manley and Marine, 1 however, reported auto-transplanted thyroids in rabbits which survived with apparently normal structure for 271 days, the animals showing “marked amelioration of symptoms of operative myxedema.” Loeb 2 in a series of heterotransplants found complete early degeneration in all cases usually much before the 18th day. Marine and Rosen 3 attempted to extend the life of homotransplants in the guinea-pig by administering anterior hypophysis extract, but these thyroid grafts remained viable for only 8 days. A method for obtaining persistent functional homotransplants of the thyroid is a desirable and important aid to experimental studies of the gland and it may have clinical significance.

We have been engaged in an extensive series of thyroid transplants in rats of the Long-Evans strain, which have been inbred since 1913. Autotransplants in these rats resulted in 100% viable grafts, if the thyroid was removed at 1 to 7 days of age and immediately grafted subcutaneously over the left ribs. The rats reached maturity with a normal growth curve and with no evidence of any glandular deficiency, gross or histological. The extreme ease with which viable autotransplants were obtained when infantile thyroid tissue was used prompted a subsequent series of homo-grafts.