Risks of irradiation of the human embryo and fetus

It is generally accepted that the embryo and the fetus have a high sensibility for irradiation. This sensibility is thought to be related to the frequent mitosis of embryonic cells. However, the conclusion that the irradiation sensibility of the embryo is larger in early states of development, is not justified. During the development in utero three phases can be distinguished, each with its own specific sensibility to irradiation. The author reviews the development-depending effects of irradiation of the human embryo and fetus. (Auth.)