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USMLE Embryo

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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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. What causes the obstruction in pyloric stenosis? treatment?
Respiratory distress syndrome
Primitive ventricle
Maternally derived; meconium
Hypertrophy of muscularis externis of pylorus; surgical incision

2. From what does bicornuate uterus arise? What is it associated with?
Right common cardinal vein and right anterior cardinal vein
Fetal and maternal
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Primitive ventricle

3. From What embryonic layer are the schwann cells from ?
Lacunae in between the chorionic villi
Mesoderm
Neural crest cells
arnold chiari associated with thoraclumbar myelomeningocele

4. What does the foramen ovale shunt blood from - to where? What is its remnant?
Right common cardinal vein and right anterior cardinal vein
can make cells
From teh lung;blood from IVC in RA to LA; fossa ovalis
Partial AP septum development; one large vessel leaves the heart - Right to left shunt

5. Which CN accounts for the anterior 2/3 of the tongues sensation and pain? how about taste?
3rd pouch
V3; VII
6-30
Partial AP septum development; one large vessel leaves the heart - Right to left shunt

6. What type of blood do umbilical veins carry? From where to where?
4th arch; 6th arch
Mesoderm
Oxygenated; placenta to fetus (IVC)
Yolk sac; 3rd week

7. Where is sonic hedgehog gene produced? What axis is it responsible in patterning?
Base of limbs in the zone of polarizing activity; ant - post
Amniotic epithelium
Surface ectoderm
Common carotid and internal carotid

8. what happens in hydrocele?
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Neural crest cells
Tunica vaginalis not fully fused
Deoxygenated blood; fetal internal iliac arteries to placenta

9. From What embryonic layer are the dorsal root and celiac ganglion from?
Endoderm
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Aortic arch and prox part of subclavian
Neural crest cells

10. By when are the neuropores supposed to fuse?
Week 3-8
80%
4th week
Week 4

11. From What embryonic layer is the eustachian tube from?
Mesoderm
Mesoderm; 3 week
Mesoderm; nucleous pulposos
Week 3-8

12. During what week do the limbs begin to form?
Week 4
Week 3-8
hypertrophy
Week 10-12; end of 1st trimester

13. What embryological structure gives rise to the coronary sinus?
Left horn of the sinus venosus
Mesoderm; 3 week
Mesoderm
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck

14. With the first breath the infant take - pulmonary vasculature resistance _______ which causes an increase in left atrial pressure
Decreased separation of hemispheres across midline; cyclopia
From endocardial cushions (ventral and dorsal meet each other)
Decreases
Surface ectoderm

15. From What embryonic layer do the ependymal cells arise?
Annular pancrease
Neuroectoderm
They are the edge of neural plate folding; all over the body
Cerebral hemisphere - thalami

16. What does the midgut form? hindgut?
is no longer intact
Arches 3 and 4
Duodenum to transverse colon; distal transverse colon to rectum
hypospadias

17. In anencephaly you see...
Hypospadias
elevated AFP
Indomethacin; blocks PG production
Polyhydramnios - Down syndrome - Esophageal/duodenal atresia - Imperforate anus - Meckel diverticulum

18. What is meckel's diverticulum? What is it associated with? What does that cause?
...
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Hypospadias

19. What are the three results of having pathology in the aorticopulmonary septum?
Transposition of great vessels (failure to spiral)- right to left shunt; tetralogy of Fallout (right to left shunt caused by skewed development of septum); persistent TA (partial septum development - also right to left shunt)
Week 3-8
primary palate
Truncus arteriosus; pulmonary trunk

20. What artery is derived branchial (aortic) arch 3?
Muscular ventricular septum; no
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
Common carotid and internal carotid
Mesencephalon

21. What causes persistent Truncus Arteriosus? What does it result in?
Decidual basalis
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Deformation
Week 8

22. Where is the most common ectopic thyroid tissue?
Oxygenated; placenta to fetus (IVC)
Tongue
Muscular ventricular septum; no
Midgut; 10th week

23. What is the mcc of renovascular hypertension in children? What does this predispose to?
ACE inhibitors - HCTZ
Surface ectoderm
XII
Renal artery stenosis;

24. What is holoprosencephaly? what eye disorder does it result in?
Neural crest cells
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Fetal alcohol syndrome; mental retardation
Decreased separation of hemispheres across midline; cyclopia

25. what invaginates to form the primitive streak?
Epiblast
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18
Prosencephalon

26. From What embryonic layer is the kidney and the adrenal cortex from?
Bulbos Cordis; right ventricle entirely
Left horn of the sinus venosus
Lots - cleft palate/lip
Mesoderm

27. Which part of pancreas contribute to body? tail? isthmus? accessory pancreatic duct?
Neuroectoderm
Ventral bud
4th pouch
Mesoderm

28. What effect does warfarin have on the fetus?
Mesoderm
Absent cerebellar vermis; cystic enlargement of 4th ventricle
Hemorrhage - bone deformities
Wolffian; mullerian

29. What is congenital pharyngocutaneous fistula? and How does it occur?
Apical ectodermal ridge
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
Lithium; valve leaflets attach to domain down low in RV- 'atrialized RV'
Surface ectoderm

30. From What embryonic layer does the brain arise?
Neuroectoderm
Decreased separation of hemispheres across midline; cyclopia
Base of limbs in the zone of polarizing activity; ant - post
Dorsal; faulty positioning of genital tubercle

31. What is an example of a syndrome that can cause abnormal neural crest migration and thus CV abnormalities?
3rd and 4th arches
DiGeorge
Mesoderm
mesoderm

32. What do the arches of the branchial apparatus correlate to?
Mesdoerm
1st
Prevent recurrent UTIs
6th aortic arch

33. Which branchial apparatus develops into the thymus?
Obliterated
No organ in each; agenesis no primordial tissue
3rd pouch
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)

34. What is an arnold chiari II malformation? through what hole does it herniate?
Aortic arch (from left side); right subclavian (on the right)
Cerebellar tonsillar herniation through foramen magnum
Synctiotrophoblast
Folate antagonists

35. From What embryonic layer does the sensory organs of the ear arise?
Neuroectoderm
Mesoderm; nucleous pulposos
Cerebral hemisphere - thalami
Surface ectoderm

36. 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?
Foregut; dorsal mesentery (mesodermal)
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Failure of the urachus to obliterate
Surface ectoderm

37. To what germ layer does the branchial pouches correlate to?
Fetal alcohol syndrome; mental retardation
Cerebellar tonsillar herniation through foramen magnum
Endoderm
Outgrowth of mesonephric as ureteric bud; most caudal

38. What embryological structure gives rise to the trabeculated parts of the left and right ventricle?
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Primitive ventricle
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Persistent connection between amniotic cavity and spinal canal; low folic acid

39. From What embryonic layer do the parafollicular cells of the thyroid arise?
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Neural crest cells
Base of limbs in the zone of polarizing activity; ant - post

40. From what arches are the neural crest cells that form the aorticpulmonary septum derived?
Primitive ventricle
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)
3 -4 -6
Ampulla

41. What are the neural crest cells and where do they come form? where do they go?
Fetal alcohol syndrome; mental retardation
They are the edge of neural plate folding; all over the body
Right common cardinal vein and right anterior cardinal vein
Mesencephalon

42. What is the fate of the cervical sinuses that develop from the 2nd -4th branchial grooves?
...
Grooves/clefts; arches; pouches
Annular pancrease
Obliterated

43. Does malformation occur during or after the embryonic period? is it due to an extrinsic or intrinsic disruption?
Neural crest cells
Greater horn of hyoid; CN IX (styloPharyngeus)
During; instrinsic
Increase in oxygen concentration which decreases prostaglandin concentration

44. What causes the transposition of the great vessels? What does it result in?
Grooves/clefts; arches; pouches
VACTERL; OCPs and maternal diabetes
Failure to spiral (aorta coming out of RV and PA coming out of left ventricle)- two completely separate systems
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)

45. What teratogen can cause vaginal clear cell adenocarcinoma in the fetus?
2; 1
Skewed development of AP septum
Thickened ectoderm at end of each developing limb
DES

46. Before birth - blood entering the LA is less than...
blood entering the RA
3rd pouch
Occiptal
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells

47. In what chromosomal disorder is horseshoe kidney commonly seen? what poles of the kidneys fuse?
Spinothalamic first
Neuroectoderm
Turners; inferior
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts

48. What is the neural plate and From what does it form?
Nicotine; preterm labor
T neuroectoderm
Ectoderm
80%

49. What causes the increase in left atrial pressure to close the fossa ovale?
Obliterated; forms tunica vaginalis
Decreased pulmonary resistance in the pulmonary vasculature
6th aortic arch
Ionizing

50. From where does the medulla form?
Outgrowth of mesonephric as ureteric bud; most caudal
Cranio - caudal; segmental
Myelencephalon
Nicotine; preterm labor