Genetic Susceptibility to Radiation Effects in Early Embryos

It has been known for a long time that the tissues in intense proliferation, i.e. those containing many dividing cells, are particularly radiosensitive. This is the law formulated as early as in 1906 by Bergonié and Tribondeau, after which the radiosensitivity of a tissue increases as its cells are less differentiated, have a greater potential of proliferation and divide more rapidly. Therefore, it can be supposed that the embryo should constitute a particularly vulnerable target for radiation, specially during the first steps of development. Among the somatic effects of radiation other than cancer, developmental effects on the unborn child are of greatest concern. The principal factors of importance for the induction of developmental effects are the dose and the stage of gestation at which it is delivered. Dose rate is also of significance, since many pathological effects on the embryo are reduced significantly by reducing the dose rate.