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Flashcards in Ch 8 Book Questions Deck (10)
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Phocomelia is most likely to be seen after maternal exposure to which teratogenic agent during the first trimester of pregnancy?
a. Alcohol
b. Aminopterin
c. Androgens
d. Ionizing radiation
e. Thalidomide

e. Thalidomide


Which of these anomalies can be attributed to a disturbance in tissue resorption?
a. Pelvic kidney
b. Cleft lip
c. Anal atresia
d. Renal agenesis
e. Amputated digit in utero

c. Anal atresia


Which of the following is responsible for the largest percentage of congenital malformations?
a. Maternal infections
b. Chemical teratogens
c. Genetically based conditions
d. Ionizing radiations
e. Unknown factors

e. Unknown factors


Folic acid deficiency is now believed to be a major cause of what class of malformations?
a. Trisomies
b. Neural tube defects
c. Ambiguous genitalia
d. Polyploidy
e. Duplications

b. Neural tube defects


Cleft palate is the result of a defect in what developmental mechanism?
a. Failure to fuse
b. Failure to merge
c. Faulty inductive tissue interaction
d. Disturbance in tissue resorption
e. Absence of normal cell death

a. Failure to fuse


An increased incidence of what condition is strongly associated with increasing maternal age?
a. Trisomy 18
b. Trisomy 21
c. Trisomy 13
d. Anencephaly
e. Ambiguous external genitalia

b. Trisomy 21


A woman who was in a car accident and sustained abdominal bruising during the fourth month of pregnancy gave birth to an infant with a cleft palate. She sued the driver of the other car for expenses associated with treatment of the birth defect and claimed that the defect was caused by the accident. You are asked to be a witness for the defense. What is your case?

The conditions that result in cleft palate occur during the second month of pregnancy. By the fourth month, the palate is normally completely established. It is almost certain that this malformation had already been established by the time of the accident.


A woman who took a new sedative during the second month of pregnancy felt nauseated after ingestion of the drug and stopped taking it after a couple of weeks. She gave birth to an infant who had a septal defect of the heart and sued the manufacturer of the drug. She said that the defect was caused by the drug that made her nauseated. You are asked to be a witness for the manufacturer. What is your case?

Although there may be a connection between the drug and the birth defect, proving a connection between an individual case and any drug, especially a new one, is very difficult. The woman’s genetic background, other drugs that she may have taken during the same period, her history of illnesses during early pregnancy, and her nutritional status should be investigated. Even in the best of circumstances, the probability that a specific malformation is caused by a particular factor can only be estimated in many cases.


What is a likely cause for a badly turned-in ankle in a newborn?

A common cause of such malformations is an insufficiency of amniotic fluid (oligohydramnios), which can place exposed parts of fetuses under excessive mechanical pressure from the uterine wall and lead to deformations of this type.


A 3-year-old child is much smaller than normal, has sparse hair, and has irregular teeth. What is a likely basis for this constellation of defects?

Dysplasia of ectodermal derivatives is a likely cause.