Medical Embryology
Exam Solutions
Course Introduction
Medical Embryology is the study of the development of the human embryo from fertilization through the fetal period. This course explores the key processes and molecular mechanisms underlying the formation of tissues, organs, and body systems, while emphasizing clinical correlations and the origins of congenital anomalies. Students will gain a foundational understanding of normal and abnormal development, integrating knowledge of genetics, cell biology, and anatomy to appreciate the clinical significance of embryological events in medical practice.
Recommended Textbook
Larsens Human Embryology 4th Edition by Gary C. Schoenwolf
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19 Chapters
247 Verified Questions
247 Flashcards
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2
Chapter 1: Introduction
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Sample Questions
Q1) The period of the fetus occurs during which weeks postfertilization?
A) 1-4
B) 1-8
C) 1-12
D) 5-38
E) 9-38
F) 13-38
Answer: E
Q2) Which phase of embryogenesis is characterized by extensive cell rearrangements that result in formation of a multilayered embryo?
A) Organogenesis
B) Cleavage
C) Oogenesis
D) Spermatogenesis
E) Fertilization
F) Gastrulation
Answer: F
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Page 3
Chapter 2: Gametogenesis, Fertilization, and First Week
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Sample Questions
Q1) Increase in the levels of which hormone prevents menstruation during a cycle in which fertilization occurs?
A) LH
B) FSH
C) GnRH
D) hCG
E) Estrogen
Answer: D
Q2) A researcher establishes mouse spermatozoa lacking one of the following two sperm-specific proteins: Izumo and CD9.Which developmental events will be perturbed in the absence of either of these proteins?
A) Spermatogenesis
B) Capacitation
C) Binding of spermatozoa to the zona pellucida
D) Fusion of the egg and spermatozoa membranes
E) Spermiogenesis
Answer: D
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Chapter 3: Second Week: Becoming Bilaminar and Fully Implanting
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Sample Questions
Q1) The early conceptus can spontaneously abort if it doesn't implant into the uterine wall and develop a uteroplacental circulation.Which vessels of the embryo directly contribute to this essential circulation?
A) Dorsal aortae
B) Precardinal veins
C) Vitelline arteries and veins
D) Allantoic arteries and veins
E) Postcardinal veins
Answer: D
Q2) A researcher inactivates the Sox17 gene in an animal model.As a result of this,one of the primary germ layers fails to form.What germ layer is most likely to be affected?
A) Ectoderm
B) Somatic mesoderm
C) Splanchnic mesoderm
D) Extraembryonic mesoderm
E) Endoderm
Answer: E
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5
Chapter 4: Third Week: Becoming Trilaminar and Establishing Body Axes
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Sample Questions
Q1) Caudal dysplasia results from defects in which developmental process?
A) Fertilization
B) Neurulation
C) Cleavage
D) Gametogenesis
E) Implantation
F) Gastrulation
Q2) A boy is admitted to the hospital for an emergency appendectomy.During surgery it is noted that the inflamed appendix is located on the left side,rather than the right side,and that the patient has situs inversus viscerum totalis.Mutations in which gene are known to cause this condition in animal models?
A) Pitx2
B) Bmp4
C) Hoxd13
D) Chordin
E) Tbx3
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Chapter 5: Fourth Week: Forming the Embryo
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Sample Questions
Q1) A researcher overexpresses the actin-binding protein Shroom in the surface ectoderm.What change in the ectodermal cells would this overexpression cause?
A) The cells would be expected to die.
B) The cells would be expected to undergo convergent extension.
C) The cells would be expected to undergo mitosis.
D) The cells would be expected to undergo meiosis.
E) The cells would be expected to undergo apical constriction.
F) The cells would be expected to undergo an epithelial-to-mesenchymal transformation
Q2) A woman has a child with spina bifida aperta.She is planning to have another child and is concerned that the second child will also have spina bifida aperta.What should her physician advise her to take daily to reduce the chances that the second child will have spina bifida aperta?
A) Aspirin
B) Warfarin
C) Accutane
D) Folic acid
E) Calcium supplements
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Chapter 6: Principles and Mechanisms of Morphogenesis and Dysmorphogenesis
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Sample Questions
Q1) A baby is born with both eye and bone defects.Genetic evaluation identified a mutation in LRP5.Which developmental signaling pathway is involved?
A) SHH
B) FGF
C) WNT
D) TGFBETA
E) NOTCH-DELTA
Q2) A 4-year-old girl develops T-cell acute lymphoblastic leukemia.Which developmental signaling pathway is involved?
A) SHH
B) FGF
C) WNT
D) TGFBETA
E) NOTCH-DELTA
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8
Chapter 7: Fetal Development and the Fetus As Patient
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Sample Questions
Q1) A developing fetus is diagnosed with congenital adrenal hyperplasia.What treatment would be appropriate for this condition?
A) Administer folic acid to the mother.
B) Administer propranolol to the mother.
C) Administer cyanocobalamin to the mother.
D) Do a fetal blood transfusion.
E) Administer dexamethasone to the mother.
Q2) A pregnant woman is told that one of the tests she has taken shows severely elevated alpha-Fetoprotein.Which defect might be present in her fetus?
A) Myeloschisis
B) Club foot
C) Chondrodysplasia
D) Cleft palate
E) Atrial septal defect
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Chapter 8: Development of the Skin and Its Derivatives
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Sample Questions
Q1) The skin consists of several definitive layers.Which layer contains the proliferating cells that replenish the skin throughout life?
A) Stratum granulosum
B) Stratum corneum
C) Stratum germinativum
D) Stratum spinosum
E) Periderm
Q2) P63 (also known as Tumor protein p73-like [TP73L]) mutations affect development of the skin in a spectrum of syndromes that include ectrodactyly ectodermal dysplasia-cleft lip/palate.Which cell layer of the skin expresses P63?
A) Stratum granulosum
B) Stratum corneum
C) Stratum germinativum
D) Stratum spinosum
Q3) Which phase of hair cell growth is the resting phase?
A) Anagen
B) Catagen
C) Exogen
D) Telogen
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Chapter 9: Development of the Musculoskeletal System
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Sample Questions
Q1) Multiple synostoses syndrome type I is due to mutations in which gene?
A) GDF5
B) BMP5
C) LRP5
D) NOGGIN
E) BMPR1A
Q2) In Poland anomaly,which muscle is absent?
A) Transverses abdominis
B) Pectoralis major
C) Quadratus lumborum
D) External oblique
E) Superficial transverse perineal muscle
Q3) When Runx2 (or Cbfa1) is genetically inactivated in mice,which cell lineage does not form?
A) Striated muscles
B) Chondrocytes
C) Osteoblasts
D) Osteoclasts
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11
Chapter 10: Development of the Central Nervous System
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Q1) A 45-year-old man develops Bell's palsy in which function of the facial (VII) cranial nerve is compromised.What specific level of the central nervous system does the facial nerve connect to?
A) Telencephalon
B) Diencephalon
C) Mesencephalon
D) Metencephalon
E) Myelencephalon
F) Spinal cord
Q2) An investigator injects a cell lineage marker into the developing ventricular zone of the ganglionic eminence of the developing forebrain.Cells in which region of the neonatal brain will be labeled?
A) Basal ganglia
B) Superior colliculus
C) Inferior colliculus
D) Neocortex
E) Brain stem
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Page 12
Chapter 11: Development of the Peripheral Nervous System
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Sample Questions
Q1) Hereditary peripheral neuropathies,such as Charcot-Marie-Tooth hereditary neuropathy,involve nerve demyelination.What cell type myelinates peripheral nerves during development?
A) Schwann cells
B) Oligodendrocytes
C) Astrocytes
D) Chromaffin cells
E) Endothelial cells
Q2) Neurogenesis in the PNS involves both positive and negative regulators.Which signaling pathway plays an essential role as a negative regulator of neurogenesis?
A) Tyrosine kinase
B) Tgfbeta
C) Integrin
D) Ephrin-Eph
E) Notch-Delta
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13
Chapter 12: Development of the Respiratory System and Body Cavities
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Sample Questions
Q1) A premature baby,born at 30 weeks,is suffering from respiratory distress.What stage of lung development would the lungs have reached at the time of delivery?
A) Alveolar
B) Saccular
C) Pseudoglandular
D) Canalicular
E) Embryonic
Q2) A premature baby is not producing sufficient surfactant.What is known to stimulate surfactant synthesis prior to birth?
A) Testosterone
B) Estrogen
C) Progesterone
D) Thyroxine
E) FSH and LH
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14
Chapter 13: Development of the Heart
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Q1) What type of cardiac defect would you expect if the conotruncal ridges failed to spiral as they fuse and divide the outflow tract?
A) Tetralogy of Fallot
B) Persistent truncus arteriosus
C) Transposition of the great vessels
D) A low atrial septal defect
E) Persistent (patent) ductus arteriosus
Q2) What part of the heart is derived from the left sinus horn?
A) Sinus venarum
B) Superior vena cava
C) Coronary sinus
D) Interatrial septum
E) Crista terminalis
Q3) Mutations in the Nkx2.5 gene can be found associated with what cardiovascular anomaly (anomalies)?
A) An aberrant cardiac conducting system
B) Atrial septal defects
C) Ventricular septal defects
D) Abnormal cardiac looping
E) All the above
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Chapter 14: Development of the Vasculature
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Sample Questions
Q1) A newborn exhibits severe cyanotic symptoms in the abdomen,pelvis,and lower limbs but not in head and neck or upper limbs.What is the most likely explanation?
A) This child has a preductal coarctation of the aorta.
B) This child has a postductal coarctation of the aorta.
C) This child has a patent ductus arteriosus.
D) This child has transposition of the great vessels.
Q2) In the fetus,oxygenated blood coming from the placenta mixes with fetal systemic blood in all of the following places EXCEPT:
A) Between the junction of the ductus venosum and inferior vena cava
B) Within the right atrium
C) Within the ductus arteriosus
D) In the left atrium
E) At the junction between the dorsal aorta and umbilical artery
Q3) What embryonic structure(s) form the right subclavian artery?
A) Aortic arch 3 and dorsal aorta
B) Only the seventh intersegmental artery
C) Aortic arch 6 and dorsal aorta
D) Aortic arch 4, dorsal aorta, and seventh intersegmental artery
E) Aortic arch 3 and the seventh intersegmental artery
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Page 16
Chapter 15: Development of the Gastrointestinal Tract
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Sample Questions
Q1) What forms the definitive anorectal canal?
A) It is completely derived from the distal hindgut.
B) Two thirds of the anorectal canal is derived from the hindgut, and one third is from the anal pit.
C) It is completely derived from the anal pit.
D) It is entirely derived from the cloacal membrane.
E) It is entirely derived from the urogenital sinus.
Q2) Based on hospital records,a 3-day-old newborn has not had a bowel movement.Upon re-examination,you notice the baby's abdomen appears bloated and the infant is beginning to run a fever.Soon after feeding,the baby also exhibits severe vomiting and can't keep anything down.As a physician,you request abdominal x-rays,and you find that the jejunum is drastically dilated,with the remainder of the lower small large intestines appearing smaller in diameter than expected.What is the likely cause?
A) An umbilical hernia
B) Pyloric atresia
C) Meckel's diverticulum
D) Hirschsprung's disease
E) An annular pancreas
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Chapter 16: Development of the Urogenital System
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Sample Questions
Q1) What renal structure arises via a mesenchymal-to-epithelial transition?
A) The nephron
B) Glomerular capillaries
C) The collecting tubules
D) The major and minor calyxes
Q2) A 4-year-old child was diagnosed with nephroblastoma,a kidney tumor.Subsequent genetic analysis of the child showed the presence of a mutation in a gene known to be associated with the development of this tumor but having a required role in renal development.What gene is it?
A) WT1 (Wilms' tumor suppressor)
B) RET
C) AMH
D) SOX9
E) SHH
Q3) Which developing kidney system ultimately becomes the definite kidney in humans?
A) Pronephric kidney
B) Mesonephric kidney
C) Metanephric kidney
D) Nephrogenic kidney
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18
Chapter 17: Development of the Pharyngeal Apparatus and Face
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Sample Questions
Q1) Researchers have shown that the mandibular prominence can be transformed into the maxillary prominence by the genetic inactivation of two homeobox transcription factors in mice.What are these two factors?
A) Msx1 and -2
B) Barx1 and Msx1
C) Dlx1 and -2
D) Dlx5 and -6
E) Dlx2 and -5
Q2) The first pharyngeal arch forms on which day of gestation?
A) 20
B) 22
C) 24
D) 27
E) 31
Q3) The stylopharyngeus muscle is innervated by which nerve?
A) Trigeminal
B) Vagus
C) Facial
D) Glossopharyngeal
E) Oculomotor
Page 19
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Chapter 18: Development of the Ears and Eyes
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Sample Questions
Q1) Researchers have shown that the various regions of the developing eye are specified by different transcription factors whose expression is induced by the adjacent tissues.Chx10 is one such factor that is required for the development of the neural retina.What growth factor regulates its expression?
A) Shh
B) TgfBeta
C) Fgf
D) Egf
E) Vegf
Q2) What are the key protein constituent(s) of the lens?
A) Melanin
B) Crystallins
C) Keratins
Q3) The number of hair and supporting cells in the inner ear is determined by which signaling pathway?
A) Planar polarity pathway
B) Wnt canonical pathway
C) Notch lateral inhibition pathway
D) Fgf signaling
E) Shh signaling
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Chapter 19: Development of the Limbs
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Sample Questions
Q1) Gli3 is essential for normal limb development.In mice,mutation of Gli3 results in which limb defect?
A) Amelia
B) Meromelia
C) Syndactyly
D) Polydactyly
E) Split hand/foot
Q2) The term arachnodactyly specifically refers to which defect?
A) Absence of the entire limb
B) Absence of part of the stylopod
C) Presence of extra digits
D) Fusion of digits
E) Absence of one or more digits
F) Elongation of the digits
Q3) Nail-patella syndrome is caused by mutations in which gene?
A) WNT7a
B) ENGRAILED-1
C) FGF8
D) NOGGIN
E) LMX1B
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