Experimental Defects in the Ear and the Upper Airways Induced by Radiation

Abstract

The large amount of knowledge which has accumulated to form a basis for developmental pathology as "a new and thrilling discipline of biology and medicine" (Gruenwald, 1949) has provided evidence that ionizing radiation affects developing and rapidly growing tissues. Recognizing the fact that different tissues react in different ways, the very first observers, half a century ago, tried to tabulate the organs and their constituents according to their degree of susceptibility to injury by x-rays. Irradiation of pregnant animals, at various stages of development of the embryo and fetus, has shown that the time of injury was the chief factor in determining the pattern of the malformation, although the dose influenced the severity of the defect. A series of papers (see references in Hicks, 1953 and 1954) disclose the mechanism by which irradiation brings about malformations and the developmental factors that determine the critical periods for these patterns. In the