The Effect of Local X-Ray Irradiation Upon the Teeth and Surrounding Tissues in Young Axolotls (Siredon Mexicanum)

Abstract

THERE are distinct advantages in the use of amphibians as experimental animals for the study of the biologic effects of x-ray irradiation. This is especially true for the larval form of the M\exican salamander axolotl (Siredon mexicanumn), which are excellent laboratory animals and can be easily raised from eggs under laboratory conditions. Their comparatively small size makes them very convenient for irradiation and for histologic examination.Our previous investigations (Brunst,3' 4and Brunst, Barnett, and Figge5 6) have shown that the reactions of tissues of axolotls to irradiation in general are very similar to such reactions in mouse tissues. Therefore, these results are significant not only for amphibians, but may also apply to higher forms. The radiobiologic literature contains a number of papers describing the effect of x-ray irradiation on teeth (Leist,These papers describe such effects of x-rays as the suppression of growth of teeth, delay in the eruption of teeth, retardation of both enamel and dentin formation, the effects of x-rays on the odontoblasts and indirect effects on the teeth of mammals. We cannot find any work in the literature describing the effects of irradiation on the teeth of amphibians. The purpose of this work was to investigate effects of x-ray irradiation on the teeth of young axolotls. MATERIAL AND METHODSThe animals were divided into 2 age groups. In the first group, 5 animals were irradiated with 2000 r 20 days after hatching, and 9 animals were irradiated with 4000 r 22 days after hatching (Vig. 2). In the second age group, 22 animals were irradiated with 3000 r 60 days after hatching (Fig. 3).During irradiation of the lower jaw, the upper jaw and skull were protected by a small lead plate which was inserted into the mouth of the anesthetized animal. The triangular lead plate was 1.5 mm. thick at the base, but at the tip, which was inserted into the mouth, it was approximately 0.5 mm thick ( Fig. 1B and C). The bodies of the experimental animals were protected by a lead plate, 4 mm. thick. Irradiations were made through a 2 cm. width Vocalizer slit. The position of the animals during irradiation is shown

The Effect of Local X-Ray Irradiation Upon the Teeth of the Adult Axolotl (Siredon Mexicanum)

“…15 and 18). The role of macrophages in the destruction of irradiated tissues has been observed many times in earlier investigations (Brunst,and Figge,(2)(3)(4)(5)(6)(7)(8)(9). Tooth substance is probably dissolved by lytic enzymes produced by the macrophages (Brunst9).…”

Investigation of the Lethal Effect of X-Irradiation on the Young Axolotl (Siredon mexicanum)

“…The dose of 6000 r is large enough for reaction of the retina to be observed soon after treatment. The animals receiving 3000 r of head irradiation only lived a comparatively long time, and damage to the retina and later disappearance of the eyes and teeth were seen according to our previous observations (17,18). DISCUSSION For comparison of the lethal effects of total-body and partial irradiation it is important to use doses large enough for reasonably early response but sufficiently small to allow observation of the treated animals long enough to note all gradations of postirradiation damage.…”

“…In another year, it was not observed in a repetition of the same experiment in which the material and conditions were presumably the same. It was not seen after irradiation of the head of the axolotl (17), but it was clearly observed after irradiation of the jaws of the same animals (18). Our knowledge of tissue reactions to irradiation is not complete, and this investigation must be continued.…”

“…It is noteworthy that after local irradiation not all the elements of the primary acute reaction were always observed. For example, the pigment layer was normal after local irradiation of the jaws of the axolotl (18). Degenerating giant cell epithelium was described in the irradiated region of the tail in one year (14).…”