Developmental toxicology

Question 1

Diethylstilbestrol (DES)

a. was used to treat morning sickness from the 1940’s to the 1970’s
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 not used to treat leprosy patients

Answer 1

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

Question 2

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)

Answer 2

c. ethanol

Question 3

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

a. ectoderm
b. mesoderm
c. epidermal placodes
d. paraxial mesoderm
e. endoderm

Answer 3

a. ectoderm

Question 4

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. pre-implantation
d. third trimester
e. first trimester

Answer 4

c. pre-implantation

Question 5

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

Answer 5

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

Question 6

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
e. M-G1, anaphase

Answer 6

b. G1-S, S, G2-M

Question 7

Which of the following molecules is NOT important in determining the ultimate outcome of embryonal DNA damage?

a. p53
b. Bax
c. Bcl-2
d. c-Myc
e. NF-kB

Answer 7

e. NF-kB

Question 8

Which of the following is NOT a physiologic response to pregnancy?

a. increased cardiac output
b. increased blood volume
c. increased peripheral vascular resistance
d. decreased plasma proteins
e. increased extracellular space

Answer 8

c. increased peripheral vascular resistance

Question 9

All of the following statements are true EXCEPT:

a. Offspring of white mothers have a higher incidence of cleft lip or palate than do black mothers, after adjusting for paternal race
b. Cytomegalovirus (CMV) is a common viral cause of birth defects
c. Folate supplementation during pregnancy decreases the risk of neural tube defects
d. Cigarette smoke and ethanol are both toxic to the placenta
e. In humans, there is a negative correlation between stress and low birth weight

Answer 9

e. In humans, there is a negative correlation between stress and low birth weight

Question 10

Which of the following is NOT a mechanism involving the endocrine system by which chemicals induce developmental toxicity?

a. acting as steroid hormone receptor ligands
b. disrupting normal function of steroid hormone metabolizing enzymes
c. disturbing the release of hormones from the hypothalamus
d. disturbing the release of hormones from the pituitary
e. elimination of natural hormones

Answer 10

e. elimination of natural hormones