THE EFFECT OF LOCAL X-RAY IRRADIATION UPON THE TEETH OF THE ADULT AXOLOTL (SIREDON MEXICANUM)

¹ Laboratory of Radiobiology, Roswell Park Memorial Institute, Buffalo, N. Y.

The anterior portion of the head, back to and including the eyes, of 20 adult axolotls (Siredon mexicanum) was irradiated with 6,000 r. During the first 50 days after treatment, only normal teeth were observed. At the end of this period they began to disappear. This process usually took place quickly within 10 to 15 days. The disappearance of teeth was a result of the activity of giant cell macrophages. Along with the disappearance of old teeth, a new generation of teeth began to form. These teeth were much smaller, irregular in shape and in position. They were never connected with the bone and only in some cases with connective tissue. These new teeth, usually unable to function, also gradually disappeared. In some animals, fixed about 150 days after irradiation, almost all teeth had disappeared and only an occasional small tooth could be found. The presence of macrophages under the root of some teeth in an animal fixed about the same time showed that the new generation of teeth also gradually disappeared as a result of the activity of macrophages.

The mechanism of tooth formation and tooth maintenance in the adult axolotl was greatly damaged by irradiation of 6,000 r.