The impact of ionizing radiations on the embryo and fetus.

Abstract

Data are presented on the major abnormalities found in mice, rats, and humans following exposure of the embryo or fetus to ionizing radiations. A schematic representation is included of the role of desoxyribonucleic acid and ribonucleic acid in protein synthesis in embryonic cells. The effects of the radiosensitivity of desoxyribonucleic acid synthesis on the induction of anomalies in the embryo or fetus are discussed. It is pointed out that radioinduced congenital abnomalies should be regarded as expressions of loss or failure of certain structures to develop rather than as the appearance of additional, new, and grotesque structures. Some gross cellular changes caused by ionizing radiations are probably permanent, irrevocable, and irreparable so that the organism as a whole rejects them and continues to develop without them if it can. This leads to changes that are most graphic when they involve the central nervous system. Anomalies of the nervous system may result from exposure at any time from fertilization of the egg to the completion of development after birth. Damage to the central nervous system in late development may be revealed only by functional tests such as electroencephalography, electroretinography, psychologic behavior, and intelligence tests. (C.H.)