High Sensitivity of Fertilized Eggs to Radiation and Chemicals in Mice: Comparison with that of Germ Cells and Embryos at Organogenesis*

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Abstract
ABSTRACT  Sensitivity of fertilized mouse eggs to X‐rays and chemicals was compared with that of parental germ cells and embryos at organogenesis. When X‐rays were given to pregnant ICR mice at about 6 hr after fertilization (pronucleus stage), there is a dramatic increase of dead embryos with X‐ray dose. A half of fertilized eggs were killed by 50 R of X‐rays, while there is no increase of dead embryos and fetuses up to 150 R when pregnant mice were treated on Day 9.5. Striking is high sensitivity of fertilized eggs to synthetic surfactants, alcohol sulfate (AS) and linear alkylbenzene sulfonate (LAS). When 0.1 ml of AS was painted on the back of pregnant mice from Day 0 to Day 2, significant numbers of deformed (dead or dying) embryos were observed. The incidence of deformed embryos increased with doses of AS. Similar results were observed with LAS, and commercially obtained kitchen detergents and shampoo.When fertilized eggs were exposed to X‐rays and chemicals at pronucleus stage (Day 0), however, tumors and anomalies were induced at very low rate if at all, while embryos at organogenesis and growing fetuses showed high susceptibility to X‐ray and chemically induced anomalies and chemically induced tumors, respectively.Parental exposure to X‐rays induced significant yields of dominant lethals, anomalies and tumors in the offspring. However, the incidences of lethals and anomalies were much lower than those induced by treatment of embryos at organogenesis with equivalent doses of X‐rays.