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1

The sclerotome arises from cells that were located in the:

A. Notochord
B. Paraxial mesoderm
C. Intermediate mesoderm
D. Lateral plate mesoderm
E. None of the above

B. Paraxial mesoderm

2

The cardiogenic plate arises from:

A. Embryonic endoderm
B. Somatic mesoderm
C. Splanchnic mesoderm
D. Intermediate mesoderm
E. Neural crest

C. Splanchnic mesoderm

3

An inductive stimulus from which structure stimulates the transformation of the epithelial sclerotome into secondary mesenchyme?

A. Neural crest
B. Somite
C. Ectodermal placodes
D. Embryonic endoderm
E. Notochord

E. Notochord

4

The intermediate mesoderm is the precursor of the:

A. Urogenital system
B. Heart
C. Somites
D. Body wall
E. Vertebral bodies

A. Urogenital system

5

The intermediate mesoderm is the precursor of the:

A. Urogenital system
B. Heart
C. Somites
D. Body wall
E. Vertebral bodies

A. Urogenital system

6

What forces are involved in the folding of the neural plate to form the neural tube?

A change in cells shape at the median hinge point and pressures of the lateral ectoderm acting to push up the lateral walls of the neural plate

7

What role do neuromeres play in the formation of the central nervous system?

Neuromeres provide the fundamental organization of parts of the brain in which they are present. Certain homeobox genes are expressed in a definite sequence along the neuromeres

8

From what structures do the cells that form skeletal muscles arise?

The somites. Axial muscles form from cells derived from the medial halves and limb muscles arise from cellular precursors located in the lateral halves of the somites

9

Where do the first blood cells of the embryo form?

In blood islands that arise from the mesoderm of the wall of the yolk sac

10

In the mature placenta, which fetal tissue directly interfaces with the maternal uterine connective tissue?

A. Cytotrophoblast
B. Syncytiotrophoblast
C. Extraembryonic mesoderm
D. Decidual cells
E. None of the above

A. Cytotrophoblast

11

Which condition is related to paternal imprinting?

A. Accessory placental lobes
B. Placenta previa
C. Oligohydramnios
D. Single umbilical artery
E. Hydatidiform mole

E. Hydatidiform mole

12

Blood vessels associated with which structure enter the fetal component of the placenta?

A. Decidua basalis
B. Allantois
C. Amnion
D. Yolk sac
E. Decidua parietalis

B. Allantois

13

What type of cells invades the maternal spiral arteries and reduces the flow of blood from their open ends?

A. Hofbauer cells
B. Syncytiotrophoblasts
C. Fetal erythrocytes
D. Cytotrophoblast
E. Amniotic epithelium

C. Fetal erythrocytes

14

Which of the following condition of the extraembryonic membranes can be found in the uteri containing identical twins?

A. Common placenta and amniotic membrane
B. Common placenta and chorion, separate amnion
C. Separate placentas and extraembryonic membranes
D. Common placentas, partially fused chorions
E. All of the above

E. All of the above

15

In the let-down of milk during lactation, the myoepithelial cells contract in response to:

A. Progesterone
B. Oxytocin
C. Estrogens
D. Lactalbumin
E. Casein

B. Oxytocin

16

Why is the human placenta designated a hemochorial type of placenta?

Because the placental villi are directly bathed in maternal blood

17

An infant with a tuft of hair over the lumbar region of the vertebral column undergoes surgery for a congenital anomaly in that region. During surgery, it was found that the dura and arachnoid layers over the spinal cord were complete, but that the neural arches of several vertebrae were missing. What condition did the infant have?

A. Meningocele
B. Meningomyelocele
C. Encephalocele
D. Spina bifida occulta
E. Rachischisis

D. Spina bifida occulta

18

Phocomelia is most likely to be seen after maternal exposure to which teratogenic agent during the first trimester of pregnancy?

A. Alcohol
B. Amniopterin
C. Androgens
D. Ionizing radiation
E. Thalidomide

E. Thalidomide

19

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

20

Folic acid deficiency is now believed to be a major cause of what class of malformation?

A. Trisomies
B. Neural tube defects
C. Ambiguous genitalia
D. Polyploidy
E. Duplications

B. Neural tube defects

21

Cleft palate is the result of a defect in what developmental feature?

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

22

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 for expenses associated with treatment of the birth defect and claimed it was caused by the accident. You are a witness for the defense, what it your case?

By the fourth month the palate is almost completely formed

23

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

insufficiency of amniotic fluid, which can place exposed parts of fetuses under pressure from the uterine wall

24

A 3 y/o 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

25

Satellite cells of muscle are activated under which of these conditions?

A. Normal muscle fiber growth
B. Muscle fiber regeneration
C. Muscle fiber hypertrophy
D. All of the above
E. None of the above

D. All of the above

26

Craniosynostosis is caused by an abnormal development course of the:

A. Foramen magnum
B. Cranial sutures
C. Basicranium
D. Jaws
E. None of the above

B. Cranial sutures

27

Which myogenic regulatory factor is expressed latest in the development of a muscle fiber?

A. Myogenin
B. MyoD
C. MRF-4
D. Myf-5
E. Pax-3

C. MRF-4

28

What component of the developing skin determines the nature of the hairs that form or the thickness of the epidermis in the fetus?

The dermis

29

A male pt has 2 bilaterally symmetrical brownish spots about 8 mm in diameter located on the skin about 3 in below each nipple. What is one explanation for them?

May be supernumentary nipples located along the caudal ends of the embryonic milk lines

30

Why is cranial bone typically not found over an area where part of the brain is missing?

Brain tissue induces the formation of surrounding membranous bone