Early Changes Induced in Purkinje Cells of Rabbit by Single Massive Doses of Roentgen Rays. ∗

Abstract

That nerve tissue is highly resistant to Roentgen radiation is well known through reports in the literature indicating that large repetitive doses will induce pathological changes in the nerve cells both in man 1 and in laboratory animals. 2 , 3 Time correlation of these changes has not been made in most of the reported studies. The present investigations were designed to clarify this matter by utilizing single massive exposures which serve as a starting point in relating histological change with elapsed time.

Twenty-five rabbits, 4 to 5 lb in weight, were irradiated in 4 groups of 6 and one singly. With the aid of a special holder, the heads of the animals were held in place in a circle of small radius and simultaneously irradiated. The dosage is listed in Table I.

The changes observed in the treated animals were chromatolysis, vacuolization of the cytoplasm, pyknosis, and loss of cells through neuronophagia. The animals killed immediately following irradiation showed marked lysis of the Nissl material of the cells. This chromatolysis is short-lived, being but slight in No. 349 which was killed at 18 hours and not to be noticed at all in the first member of the 1000 r series. Rabbit No. 408, killed immediately after irradiation shows cells which demonstrate not only complete breaking up of the Nissl bodies into a fine lightly staining powder, but also reveal the appearance at the periphery of the cell of a wide margin of clear cytoplasm. Neighboring cells show large clear vacuoles occupying this marginal zone and in some instances replacing entirely the unstained cytoplasm. Further studies on the relationship of the chromatolysis, the appearance of the clear margin of cytoplasm, and the vacuolization are being made.

Pyknosis of some cells is seen in the early members of the series and becomes more marked in those killed later. Neuronophagia is not observed where less than 24 hours had elapsed following irradiation. It is severe in all of the later instances.