Developing Human Clinically Embryology 9th Edition Moore Persaud-Test Bank
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Sample
Test
Moore: The Developing Human, 9th Edition
Chapter 03: Formation of Germ Layers and Early Tissue and Organ
Differentiation
Test Bank
MULTIPLE CHOICE
Directions: Each group of questions below consists of a numbered
list of descriptive words or phrases accompanied by a diagram with certain
parts indicated by letters and a list of lettered headings. For each numbered
word or phrase, select the lettered part or heading that matches it correctly
and then insert the letter in the space to the right of the appropriate number.
Sometimes more than one numbered word or phrase may be correctly matched to the
same lettered part or heading.
1.
________ Notochordal process
1. A
2. B
3. C
4. D
5. E
ANS: B
The notochordal process is a rod-shaped structure composed of
cells derived from the primitive node of the primitive streak. It is the
primordium of the notochord, a cellular structure that defines the primordial axis
of the embryo.
2.
________ Site of the prechordal plate
1. A
2. B
3. C
4. D
5. E
ANS: A
The site of the prechordal plate is indicated in the drawing by
a dotted oval to indicate that it is not visible from the dorsal surface of the
embryonic disc. The prechordal plate is a circular area of thickened embryonic
endoderm in the cranial part of the roof of the umbilical vesicle. The
prechordal plate, together with the overlying embryonic ectoderm, later
constitutes the oropharyngeal membrane.
3.
________ Gives rise to most of the embryonic mesoderm
1. A
2. B
3. C
4. D
5. E
ANS: D
The primitive streak, a linear band of epiblast, gives rise to
mesoderm mainly during the third week. The mesoderm extends laterally and
becomes continuous with the extraembryonic mesoderm on the amnion and umbilical
vesicle.
4.
________ Primitive pit
ANS: C
The primitive pit is a depression in the primitive node at the
cranial end of the primitive streak. It extends into the notochordal process
and forms the notochordal canal. Thus, it is the entrance to the notochordal
canal. The pit later forms the opening of the neurenteric canal, which
temporarily connects the amniotic cavity with the umbilical vesicle.
5. ________
Aggregation of angioblasts
6. Allantois
7. Primitive
streak
8. Notochord
9. Blood
island
10. Neural
plate
ANS: D
Splanchnic mesenchymal cells known as angioblasts aggregate to
form isolated masses called blood islands, which develop into vascular
endothelium and primordial blood cells. Blood islands form first on the
umbilical vesicle, chorion, allantois, and connecting stalk, but they develop
in the embryo about 2 days later.
6. ________
Diverticulum of umbilical vesicle (yolk sac)
7. Allantois
8. Primitive
streak
9. Notochord
10. Blood
island
11. Neural
plate
ANS: A
The allantois, a diverticulum of the umbilical vesicle, is a
vestigial structure that later becomes the urachus (median umbilical ligament
in an adult). It serves as a reservoir for excretory products in some species,
but it is nonfunctional in human embryos. However, its blood vessels become the
umbilical vessels.
7. ________
Forms the basis of the axial skeleton
8. Allantois
9. Primitive
streak
10. Notochord
11. Blood
island
12. Neural
plate
ANS: C
The developing notochord and the adjacent paraxial mesoderm are
thought to produce inductive substances that stimulate development of the
neural plate from the overlying embryonic ectoderm. The notochord forms the
basis of the axial skeleton. The vertebrae develop around it, and then it
degenerates. In between the vertebrae, the notochord forms the primordium of
the nucleus pulposus of the intervertebral disc.
8. ________
Gives rise to the brain and spinal cord
9. Allantois
10. Primitive
streak
11. Notochord
12. Blood
island
13. Neural
plate
ANS: E
The neural plate is a thickened area of ectoderm that overlies
and extends on each side of the notochord. The neural plate invaginates to form
a neural groove. In later development, the neural folds meet dorsally and fuse
to form the neural tube. The cranial part of the neural tube develops into the
brain, and the longer remaining part forms the spinal cord. The notochord and
paraxial mesoderm produce inductive substances that stimulate or induce the
overlying ectoderm to thicken and form the neural plate.
9. ________
Source of mesenchyme
10. Allantois
11. Primitive
streak
12. Notochord
13. Blood
island
14. Neural
plate
ANS: B
The primitive streak produces mesoderm, which develops into
mesenchyme (embryonic connective tissue). Mesenchyme forms a packing tissue
around developing organs and develops into connective tissues and muscles.
10. ________
Appears on extraembryonic membranes
11. Allantois
12. Primitive
streak
13. Notochord
14. Blood
island
15. Neural
plate
ANS: D
The blood islands first appear on the walls of the umbilical
vesicle, allantois, and connecting stalk. These extraembryonic membranes are
derived from the zygote, but they are not part of the embryo. Blood islands
form in the embryo about 2 days after they appear on the umbilical vesicle.
11.
________ Wall of amniotic sac
1. A
2. B
3. C
4. D
5. E
ANS: C
The amnion encloses the amniotic cavity, forming an amniotic
sac. It contains fluid that bathes the embryonic disc, forming its floor. The
wall of this sac consists of an inner epithelial layer of cells covered
externally by extraembryonic somatic mesoderm.
12.
________ Neural groove
1. A
2. B
3. C
4. D
5. E
ANS: A
The neural groove forms as the neural plate invaginates to form
a neural fold on each side. The folds later fuse to form the neural tube, the
primordium of the central nervous system (brain and spinal cord). The ectoderm
lateral to the folds, surface ectoderm, gives rise to the epidermis of the
skin.
13.
________ Derived from primitive streak
1. A
2. B
3. C
4. D
5. E
ANS: E
The intraembryonic mesoderm is derived from the primitive
streak. The primitive streak produces mesoderm rapidly during the third and
fourth weeks.
14.
________ Embryonic ectoderm
1. A
2. B
3. C
4. D
5. E
ANS: B
The embryonic ectoderm in the region indicated forms a neural
fold. The neural folds soon fuse, converting the neural plate into the neural
tube.
15.
________ Derived from paraxial mesoderm
1. A
2. B
3. C
4. D
5. E
ANS: C
The somites are paired cubical masses derived by segmentation of
the paraxial mesoderm. The first pair of somites is formed a short distance
caudal to the tip of the notochord, and successive somites are progressively
formed from paraxial mesoderm. Most somites appear between days 20 and 30; they
give rise to the axial skeleton and its associated musculature.
16.
________ Derived from notochordal process
1. A
2. B
3. C
4. D
5. E
ANS: E
The notochord arises by transformation of the notochordal
process. The notochord is a cellular rod that defines the primordial axis of
the embryo. Mesenchymal cells from the somites later surround it and give rise to
the mesenchymal bodies of the vertebrae. The notochord within the developing
vertebrae later degenerates.
17.
________ Gives rise to an adult body cavity
1. A
2. B
3. C
4. D
5. E
ANS: A
The intraembryonic coelom in the area indicated becomes part of
the peritoneal cavity. The coelom appears here as a space within the lateral
mesoderm, splitting it into somatic and splanchnic layers. The transverse
section is cut through the caudal region of the lateral extensions of the
horseshoe-shaped body cavity or coelom.
18.
________ Splanchnopleure
1. A
2. B
3. C
4. D
5. E
ANS: D
The splanchnopleure is composed of splanchnic mesoderm and
endoderm and represents the future wall of the primordial gut. The endoderm
gives rise to the epithelium and glands of the digestive tract, and the
mesoderm gives rise to its muscular and fibrous elements.
19.
________ Fusing to form neural tube
1. A
2. B
3. C
4. D
5. E
ANS: B
The neural folds are fusing to form the neural tube, the
primordium of the brain and spinal cord. These folds form as the neural plate
invaginates along its central axis to form a neural groove.
20.
________ Umbilical artery
1. A
2. B
3. C
4. D
5. E
ANS: B
The paired umbilical arteries are branches of the dorsal aortae.
They transport deoxygenated blood and waste products from the embryo to the
chorionic villi of the placenta.
21.
________ Vitelline artery
1. A
2. B
3. C
4. D
5. E
ANS: E
The vitelline arteries are branches of the dorsal aortae to the
umbilical vesicle. The vitelline arteries and vitelline veins are in communication
through the vascular plexus on the umbilical vesicle.
22.
________ Sinus venosus
1. A
2. B
3. C
4. D
5. E
ANS: A
Blood enters the sinus venosus from the embryo through the
cardinal veins, from the developing placenta via the umbilical vein, and from
the umbilical vesicle via the vitelline veins. Blood from the sinus venosus
enters the primordial heart.
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