18.Which of the following is in direct contact with maternal blood in
lacunae of the placenta?
a. Cells of the cytotrophoblast
b. Extraembryonic mesoderm
c. Fetal blood vessels
d. Cells of the syncytiotrophoblast
e. Amniotic cells
19.A dental hygienist is concerned about the effects of radiation on the in
uterodevelopment of her baby. During which of the following periods is the
embryo most susceptible to environmental influences that could induce
the formation of nonlethal congenital malformations?
a. Fertilization to 1 week of fetal life
b. The second week of fetal life
c. The third through eighth weeks of fetal life
d. The third month of fetal life
e. The third trimester of fetal life
20.During a visit to her gynecologist, a patient reports she received vita-
min A treatment for her acne unknowingly during the first 2 months of an
undetected pregnancy. Which of the following organ systems in the devel-
oping fetus is most likely to be affected?
a. The digestive system
b. The endocrine organs
c. The respiratory system
d. The urinary and reproductive systems
e. The skeletal and central nervous systems
21.A 32-year-old (gravida 2, para 1) female presents to her obstetrician
with abdominal discomfort, increased back pain, shortness of breath, and
swelling in her feet and ankles. Ultrasound reveals an amniotic fluid index
(AFI) of 27 cm (normal 5 to 24 cm). The condition is caused by which of
the following?
a. Duodenal or esophageal atresia
b. Bilateral agenesis of the kidneys
c. Precocious development of the swallowing reflex in the fetus
d. Hypoplasia of the lungs
e. Obstructive uropathy
Embryology: Early and General 77