The embryonal stage in @entity1 is characterized by a quick proliferation and differentiation of cells. The special features of this stage of development in all living beings is therefore an increased sensitivity for the exposure with ionizing radiation. Radiation exposure during the prenatal development can therefore lead to @entity73 , which can be short-termed or long-termed, showing effects even in the postnatal period. The pattern of radiation induced effects is dependent upon the radiation dose on the one hand and upon the stage of fetal development when radiation exposure occurs on the other hand. Radiation induced effects can be @entity851 , @entity73 or @entity204 as well as increased occurrence of @entity5 and @entity1778 during childhood. The main effects of a radiation exposure in the fetal period are: 1) lethal effects for the embryo, 2) @entity600 and changes in growth or other functional changes, 3) @entity1032 , 4) induction of malignomas including @entity1778 . Lethal effects can be induced experimentally in animals by relatively low radiation doses of 10 cGy, administered before or immediately after the implantation of the embryo. Malformations can be induced if the exposure occurs during the period of organogenesis especially if the radiation exposure occurs during the active stage of increased cell formation and cell differentiation of a specific organ. For many types of effects of ionizing radiation especially for the @entity204 of the embryo or fetus and for macroscopic anatomical @entity600 a dose-effect relationship with certain threshold doses can be supposed. This threshold dose is not smaller than 5 cGy if the exposure results from a low level radiation with low LET> Radiation exposure at the end of the organogenesis and during the following fetal period can induce @entity851 and functional disturbances, which are characterized by abnormalities in the postnatal period. Of special importance are the abnormalities of the CNS, like @entity1032 particularly if the radiation exposure occurred during the interval between the 8th and 15th week of pregnancy. During that time period cell formation for the development of the frontal brain occurs. The induction of this @entity66 as well as of other @entity600 is due to non stochastic effects. A threshold dose of 5 cGy ist discussed. The induction of @entity5 and @entity1778 as a consequence of a radiation exposure in the prenatal period is to be seen as a deterministic (non stochastic) radiation effect. The sensitivity of the fetus for these effects ist 2 to 3 times higher than that of adults.

[Exposure to radioactive iodine in pregnancy: significance for mother and XXXX ].

@entity1 :: ('9606', 'Species') :: ['mammalians'] @entity1032 :: ('MESH:D008607', 'Disease') :: ['mental retardation'] @entity851 :: ('MESH:D006130', 'Disease') :: ['growth retardation'] @entity66 :: ('MESH:D004194', 'Disease') :: ['type of abnormalities'] @entity5 :: ('MESH:D009369', 'Disease') :: ['malignancies', 'cancer'] @entity73 :: ('MESH:D003072', 'Disease') :: ['various impairments', 'malformations, functional impairments'] @entity600 :: ('MESH:D000014', 'Disease') :: ['malformations', 'malformation'] @entity1778 :: ('MESH:D007938', 'Disease') :: ['leukemia'] @entity204 :: ('MESH:D003643', 'Disease') :: ['death']
@entity1 :: (9606,Species) :: ['child']
