week 9 life shortening, in-utero effects, genetic effects

preimplantation stage = ?

all-or-nothing effect

what is the most radiosensitive system during organogenesis

CNS

greatest sensitivity for severe mental retardation ?

8-15weeks

what is the threshold for severe mental retardation

0.2-0.3 Gy

what is the threshold for IQ reduction

100 mGy

what is the dose reduction in life expectancy after acute exposure

1-5% per Sv

what is the main fetal-stage stochastic effect?

carcinogenesis

what is the main risk during preimplantation

prenatal death

what are the three stages of embryonic development relevant to radiation biology

preimplantation, organogenesis, fetal stage

What is the time period of the preimplantation stage?

0-9 days post-conception

What does the phrase "all-or-nothing effect" mean?

The embryo either dies or survives and develops normally.

What is the LD50 for radiation during preimplantation (mouse data)?

Approximately 1 Gy.

When does organogenesis occur?

Approximately 10 days to 6 weeks gestation.

Name three effects of irradiation during organogenesis.

Organ malformations, microcephaly, intrauterine growth retardation.

What is the fetal stage primarily characterized by?

Growth and maturation

During which fetal weeks is the nervous system particularly sensitive?

8-16 weeks