Test your basic knowledge |

USMLE Embryo

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. Cleft palate is a failure of formation of the...
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
secondary palate
Dorsal; faulty positioning of genital tubercle
Upper 1/3; urogenital sinus

2. What does the first branchial pouch create?
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells
Incomplete; yes
Spinothalamic first
...

3. What is the most common subtype of tracheoesophageal fistula? name some symptoms (hint: O2 levels - feeding - stomach on CXR - - amnios? - NG tube? - respiratory infection? )
Blind upper esophagus with lower esophagus connected to trachea; cyanosis - choking and vomiting with feeding; air bubble on CXR; polyhydramnios; failure to pass NG tube; pneumonitis
hypospadias
Failure to spiral (aorta coming out of RV and PA coming out of left ventricle)- two completely separate systems
Week 3; primitive streak formation from the epiblast makes the three layers

4. Where does fertilization occur?
arnold chiari associated with thoraclumbar myelomeningocele
Ampulla
Spinothalamic first
Mesoderm

5. What is holoprosencephaly? what eye disorder does it result in?
Before getting pregnant!
2nd pouch
Diencephalon
Decreased separation of hemispheres across midline; cyclopia

6. Which CN accounts for the anterior 2/3 of the tongues sensation and pain? how about taste?
Surface ectoderm
V3; VII
Increase in oxygen concentration which decreases prostaglandin concentration
Sperm plus egg

7. How many components are there to the placenta? What are they called?
Fetal and maternal
hypertrophy
IX; X
Thickened ectoderm at end of each developing limb

8. which teratogen can cause Ebsteins anomaly in the fetus?
Lithium
Failure to spiral (aorta coming out of RV and PA coming out of left ventricle)- two completely separate systems
Neural crest cells
Sonic Hedgehog

9. From where does the medulla form?
Myelencephalon
Bulbourethral glands (of Cowper) and Prostate gland; greater vestibular glands (of Bartholin) and Urethral and paraurethral glands (of Skene)
Oxygenated; placenta to fetus (IVC)
Surface ectoderm

10. What results in annular pancreas? How does it happen?
Decreased pulmonary resistance in the pulmonary vasculature
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Hepatic circulation; ligamentum venosum
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells

11. Where is the FGF gene produced? What is it responsible for - How does it do this?
Mesoderm; nucleous pulposos
Apical ectodermal ridge; limb lengthening; stimulates mitosis of underlying mesoderm
Week 8
Indomethacin; blocks PG production

12. what junction is the last to canalize? what implications does this have down the line?
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Alkylating agents
Occiptal
Neuroectoderm

13. What is the effect of teratogens before week 3?
All or none
Valproate acid
Blind upper esophagus with lower esophagus connected to trachea; cyanosis - choking and vomiting with feeding; air bubble on CXR; polyhydramnios; failure to pass NG tube; pneumonitis
hypertrophy

14. From What embryonic layer do the salivary - sweat and mammary glands arise?
Skewed development of AP septum
Surface ectoderm
Endoderm
Where the epiblast and hypoblast fuse

15. what week do the genitalia start to have male/female characteristics? What trimester is that?
Foregut; dorsal mesentery (mesodermal)
Endoderm
Week 10-12; end of 1st trimester
Prosencephalon

16. What is the primitive streak? From what layer does it form?
Mesoderm; epiblast
Week 3; primitive streak formation from the epiblast makes the three layers
Surface ectoderm
mesoderm

17. The spinal cord is made from...
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Midgut; 10th week
T neuroectoderm
Neuroectoderm

18. From what region of the brain does the fourth ventricle form?
Week 8
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Rhombencephalon
Pronephros - mesonephros - metanephros; pronephros; most cranially

19. From What embryonic layer does the retina arise?
Neuroectoderm
Ventral shaft of penis (penile urethra); labia minora
Week 2; bilaminar disk; epiblast and hypoblast
Sperm plus egg

20. what separates the atria from the ventricles?
No organ in each; agenesis no primordial tissue
Blind upper esophagus with lower esophagus connected to trachea; cyanosis - choking and vomiting with feeding; air bubble on CXR; polyhydramnios; failure to pass NG tube; pneumonitis
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Endocardial cushions

21. What two things cause VACTERL syndrome?
Lithium
OCPS and maternal diabetes
Hypospadias
Maternally derived; meconium

22. From What embryonic layer is aorticopulmonary septum from ?
Neural crest cells
Upper 1/3; urogenital sinus
Outgrowth of mesonephric as ureteric bud; most caudal
1st cleft/groove (Ectoderm)

23. what closes the ductus arteriousus?
Common carotid and internal carotid
Increase in oxygen concentration which decreases prostaglandin concentration
Neural crest migration - they then cause spiral
Prevent recurrent UTIs

24. What is the most common autopsy finding in brains of premature infants?
primary palate
Ventral shaft of penis (penile urethra); labia minora
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Germinal matrix hemorrhage

25. What is the female remnant of the gubernaculum? male remnant?
OCPS and maternal diabetes
Truncus arteriosus; pulmonary trunk
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Neural plate; closes by week 4

26. From What do the embryoblast and trophoblast form from? What does the embryoblast split into? the trophoblast?
Thalidomide; nausea
4th arch; 6th arch
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks

27. What three layers form during gastrulation? From What do they form? and what week does gastrulation occur?
Fetal and maternal
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18
Neuroectoderm

28. What components do the mesoderm of the branchial arches give rise to?
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Neuroectoderm
Muscles and arteries
During; instrinsic

29. What does the ductus arteriosus shunt blood away from - to where? What is its remnant?
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Dorsal; faulty positioning of genital tubercle
Synctiotrophoblast

30. What causes the obstruction in pyloric stenosis? treatment?
mesoderm
Hypertrophy of muscularis externis of pylorus; surgical incision
Primitive ventricle
Bulbourethral glands (of Cowper) and Prostate gland; greater vestibular glands (of Bartholin) and Urethral and paraurethral glands (of Skene)

31. In both meningocele and myelomeningocele the dura...
is no longer intact
Renal artery stenosis;
Failure of the urachus to obliterate; outpouching of the bladder
Amniotic cavity and yolk sac

32. What causes a patent foramen ovale?
Week 8
Excessive resorption of septum primum or secondum (or both)
Neural crest cells
Bone/cartilage and nerves

33. What day is the amnion formed?
Bones - cartilage - and nerves
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus
8
Surface ectoderm

34. Blood coming in the umbilical vein is ____ saturated
During; instrinsic
3
80%
Ventral; failure of urogenital folds to close

35. At what week does the fetus look like a baby?
4th/5th branchial pouches
Week 8
5th
They are the edge of neural plate folding; all over the body

36. ______________ is associated with ventral curvature of the penis
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
Tetracyclines
hypospadias
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts

37. From What embryonic layer is the eustachian tube from?
secondary palate
Mesoderm
Midgut; 10th week
Cleft lip/palate

38. Where is the decidua basalis derived from?
Endometrium
XII
Neural crest cells
Synctiotrophoblast

39. From what germ layer does the primitive heart tube arise?
Foregut; dorsal mesentery (mesodermal)
Mesoderm
Neural crest cells
Neuroectoderm

40. When does erythropoeisis begin in the bone marow?
Incomplete; yes
Primitive ventricle
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
28 week onward

41. What teratogen can cause inhibition of intestinal folate absorption and thus neural tube defects?
Synctiotrophoblast
septum primum and/or secundum
Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch sensation
Valproate acid

42. How many umbilical arteries are there? How many umbilical veins?
OCPS and maternal diabetes
2; 1
lumbosacral
80%

43. what bone/cartilage and nerves are derived from branchial arch 2?
Incomplete; yes
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Sonic Hedgehog
Decreased pulmonary resistance in the pulmonary vasculature

44. What is the mcc of renovascular hypertension in children? What does this predispose to?
Found in lateral neck; from no obliteration of 2-4th clefts
Neural crest cells
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus
Renal artery stenosis;

45. From where does the prostate develop? seminal vesicles? fallopian tube? lower 2/3 of the vagina? ejaculatory duct? epididymis? uterus? upper 1/3 of the vagina?
Mesoderm
Mesoderm
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Prevent recurrent UTIs

46. What are the two components of the fetal component of the placenta?
Cytotrophoblast and synctiotrophoblast
Endoderm
Deoxygenated blood; fetal internal iliac arteries to placenta
Arnold chiari; syringomyelia

47. By what week is there fetal movement?
Week 8
Blind upper esophagus with lower esophagus connected to trachea; cyanosis - choking and vomiting with feeding; air bubble on CXR; polyhydramnios; failure to pass NG tube; pneumonitis
Mental retardation - holoprosencephaly - facial features - fistulas
Fallopian tube - uterus - upper 1/3 of vagina

48. Which CN allows for taste and sensation in the posterior 1/3 of the tongue? how about the very back ?
Ventral ; motor
IX; X
Nutrient and gas exchange
Neuroectoderm

49. Where is the mothers blood located in the placenta?
Hepatic circulation; ligamentum venosum
Hemorrhage - bone deformities
Lacunae in between the chorionic villi
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects

50. Gastroschisis is extrusion of abdominal contents out of abdominal folds ___________ by peritoneum
All 3
hypertrophy
Renal artery stenosis;
not covered