Chapter 28
Pregnancy and Human Development
1093
28
Assisted Reproductive Technology and Reproductive
Cloning
(pp. 1089–1091)
1.
Assisted reproductive technology (ART) procedures assist infertile
couples to bear children. Among the most-used techniques are
IVF, ZIFT, and GIFT. IVF and ZIFT attempt to fertilize harvested
oocytes in vitro and then return the embryo or zygote to the
woman’s body. GIFT utilizes in vivo methods—sperm and oocytes
are transferred together to the woman’s uterine tubes.
2.
Reproductive cloning in humans has proved difficult to achieve
and the practice has met several roadblocks.
3.
True milk is produced around day 3 in response to suckling,
which stimulates the hypothalamus to prompt anterior pituitary
release of prolactin and posterior pituitary release of oxytocin.
Prolactin stimulates milk production. Oxytocin triggers milk let-
down. Continued breast-feeding is required for continued milk
production.
4.
At first, ovulation and menses are absent or irregular during
nursing, but in most women the ovarian cycle is eventually
reestablished while still nursing.
Multiple Choice/Matching
(Some questions have more than one correct answer. Select the best
answer or answers from the choices given.)
1.
Indicate whether each of the following statements is describing
(a)
cleavage or
(b)
gastrulation.
____
(1)
period during which a morula forms
____
(2)
period when vast amounts of cell migration occur
____
(3)
period when the three embryonic germ layers appear
____
(4)
period during which the blastocyst is formed
2.
Most systems are operational in the fetus by four to six months.
Which system is the exception to this generalization, affecting
premature infants?
(a)
the circulatory system,
(b)
the respiratory
system,
(c)
the urinary system,
(d)
the digestive system.
3.
±e zygote contains chromosomes from
(a)
the mother only,
(b)
the father only,
(c)
both the mother and father, but half from
each,
(d)
each parent and synthesizes others.
4.
±e outer layer of the blastocyst, which later attaches to the
uterus, is the
(a)
decidua,
(b)
trophoblast,
(c)
amnion,
(d)
inner
cell mass.
5.
±e fetal membrane that forms the basis of the umbilical cord is
the
(a)
allantois,
(b)
amnion,
(c)
chorion,
(d)
yolk sac.
6.
In the fetus, the ductus arteriosus carries blood from
(a)
the
pulmonary artery to the pulmonary vein,
(b)
the liver to the
inferior vena cava,
(c)
the right ventricle to the le² ventricle,
(d)
the pulmonary trunk to the aorta.
7.
Which of the following changes occur in the baby’s
cardiovascular system a²er birth?
(a)
Umbilical arteries and vein
become fibrosed,
(b)
pulmonary circulation begins to function,
and pressure in the le² side of the heart increases,
(c)
the ductus
venosus becomes obliterated, as does the ductus arteriosus,
(d)
all of these.
8.
Following delivery of the infant, the delivery of the a²erbirth
includes the
(a)
placenta only,
(b)
placenta and decidua,
(c)
placenta and attached (torn) fetal membranes,
(d)
chorionic
villi.
9.
±e umbilical vein carries
(a)
waste products to the placenta,
(b)
oxygen and food to the fetus,
(c)
oxygen and food to the
placenta,
(d)
oxygen and waste products to the fetus.
10.
±e germ layer from which the skeletal muscles, heart, and
skeleton are derived is the
(a)
ectoderm,
(b)
endoderm,
(c)
mesoderm.
11.
Which of the following cannot pass through placental barriers?
(a)
blood cells,
(b)
glucose,
(c)
amino acids,
(d)
gases,
(e)
antibodies.
12.
±e most important hormone in initiating and maintaining
lactation a²er birth is
(a)
estrogen,
(b)
FSH,
(c)
prolactin,
(d)
oxytocin.
13.
±e initial stage of labor, during which the neck of the uterus
is stretched, is the
(a)
dilation stage,
(b)
expulsion stage,
(c)
placental stage.
14.
Match each adult structure in column B with the embryonic
structure it derives from in column A.
Column A
____
(1)
notochord
____
(2)
ectoderm (not
neural tube)
____
(3)
intermediate mesoderm
____
(4)
lateral plate mesoderm
____
(5)
sclerotome
____
(6)
coelom
____
(7)
neural tube
____
(8)
endoderm
Review Questions
Column B
(a)
kidney
(b)
peritoneal cavity
(c)
pancreas, liver
(d)
parietal serosa, dermis
(e)
nucleus pulposus
(f)
hair and epidermis
(g)
brain
(h)
ribs and vertebrae
Short Answer Essay Questions
15.
What is the function of hCG and why is it not important a²er the
first trimester of pregnancy?
16.
Fertilization involves much more than a mere restoration of
the diploid chromosome number. (a) What does the process of
fertilization entail on the part of both the egg and sperm?
(b) What are the effects of fertilization?
17.
Cleavage is an embryonic event that mainly involves mitotic
divisions. How does cleavage differ from mitosis occurring
during life a²er birth, and what are its important functions?
18.
±e life span of the ovarian corpus luteum is extended for nearly
three months a²er implantation, but otherwise it deteriorates.
(a) Explain why this is so. (b) Explain why it is important that
the corpus luteum remain functional following implantation.
19.
±e placenta is a marvelous, but temporary, organ. Starting with
a description of its formation, show how it is an intimate part
of both fetal and maternal anatomy and physiology during the
gestation period.
20.
Why is it that only one sperm out of the hundreds (or thousands)
available enters the oocyte?
21.
What is the function of gastrulation?
22.
Cite two problems with a breech presentation.
23.
What factors are believed to bring about uterine contractions at
the termination of pregnancy?
24.
Explain how the flat embryonic disc takes on the cylindrical
shape of a tadpole.
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