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Chapter 10. Developmental Toxicology

Diethylstilbestrol (DES):

a. was used to treat morning sickness from the 1940s to the 1970s.

b. was found to affect only female offspring in exposed pregnancies.

c. greatly affects the development of the fetal brain.

d. exposure increases the risk of clear cell adenocarcinoma of the vagina.

e. is now used to treat leprosy patients.

Early (prenatal) exposure to which of the following teratogens is most often characterized by craniofacial dysmorphism?

a. thalidomide.

b. retinol.

c. ethanol.

d. tobacco smoke.

e. diethylstilbestrol (DES).

The nervous system is derived from which of the following germ layers?

a. ectoderm.

b. mesoderm.

c. epidermal placodes.

d. paraxial mesoderm.

e. endoderm.

Toxin exposure during which of the following periods is likely to have the LEAST toxic effect on the developing fetus?

a. gastrulation.

b. organogenesis.

c. preimplantation.

d. third trimester.

e. first trimester.

Regarding prenatal teratogen exposure, which of the following statements is FALSE?

a. Major effects include growth retardation and malformations.

b. Exposure to teratogens during critical developmental periods will have more severe effects on the fetus.

c. There is considered to be a toxin level threshold below which the fetus is capable of repairing itself.

d. The immune system of the fetus is primitive, so the fetus has little to no ability to fight off chemicals and repair itself.

e. Embryo lethality becomes more likely as the toxic dose is increased.

Which of the following stages of the cell cycle are important in monitoring DNA damage and inhibiting progression of the cell cycle?

a. G1–S, anaphase, M–G1.

b. G1–S, S, G2–M.

c. S, prophase, G1.

d. G2–M, prophase.

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