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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. Name a syndrome cleft palate is often seen in
Bone/cartilage and nerves
DiGeorge
Endoderm - floor of primitive pharynx
Surface ectoderm

2. By what week is there fetal movement?
Mesoderm
Hypertrophy of muscularis externis of pylorus; surgical incision
Week 8
Neuroectoderm

3. From What embryonic layer do the parafollicular cells of the thyroid arise?
Base of limbs in the zone of polarizing activity; ant - post
Indomethacin; blocks PG production
Neural crest cells
Rhombencephalon

4. What is the memranous interventricular formaen made from?
Cytotrophoblast
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Nicotine; preterm labor
Where the epiblast and hypoblast fuse

5. During what months is the fetus most susceptible to teratogens? What trimester?
Physiologic incomplete muscular ventricular septum
Embryonic period; 1st trimester
3rd pouch
Neuroectoderm

6. WithIn what week does gastrulation occur? What is gastrulation?
hypertrophy
Bone/cartilage and nerves
Week 3; primitive streak formation from the epiblast makes the three layers
Synctiotrophoblast; outer; no

7. What does the foramen ovale shunt blood from - to where? What is its remnant?
Base of limbs in the zone of polarizing activity; ant - post
From teh lung;blood from IVC in RA to LA; fossa ovalis
Telencephalon
All 3

8. Pyloric stenosis is characterized by _____________ of muscularis externis in the sphincter
Surface ectoderm
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
hypertrophy

9. What is the most common subtype of tracheoesophageal fistula? name some symptoms (hint: O2 levels - feeding - stomach on CXR - - amnios? - NG tube? - respiratory infection? )
Lithium
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
is no longer intact
Mesoderm

10. Which branchial derivative accounts for taste in the ant 2/3?
DES
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Branchial arch 2

11. Which branchial derivative accounts for the sensation and taste in the posterior 2/3 of the tongue? how about the very back?
Fallopian tube - uterus - upper 1/3 of vagina
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Spinothalamic first
4th arch; 6th arch

12. From what are the umbilical arteries and veins derived from?
Sperm plus egg
Allantois
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
Common carotid and internal carotid

13. From where does the permanent kidney for? is it most caudal or most cranial?
Hypertrophy of muscularis externis of pylorus; surgical incision
Dorsal; sensory
IX; X
Outgrowth of mesonephric as ureteric bud; most caudal

14. What are the two components of the placenta? From What do they form? which one secreted hcG?
Neural crest cells
Mental retardation - holoprosencephaly - facial features - fistulas
...
Dorsal and ventral buds

15. From What embryonic layer does the neurohypophysis arise?
Neuroectoderm
Mesoderm
Fetal and maternal
DHT; estrogen

16. The notochord is...
From teh lung;blood from IVC in RA to LA; fossa ovalis
Vascular accident intra uterine; apple peel atresia
mesoderm
Ventral; failure of urogenital folds to close

17. What is the difference between agenesis and aplasia?
Mesoderm
No organ in each; agenesis no primordial tissue
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
Neuroectoderm

18. What artery is derived branchial (aortic) arch 4?
Aortic arch and prox part of subclavian
Neural plate; closes by week 4
Nutrient and gas exchange
Bulbos Cordis; right ventricle entirely

19. What is hypoplasia? is primordial tissue present?
Neuroectoderm
Incomplete; yes
Endoderm - floor of primitive pharynx
ACE inhibitors - HCTZ

20. What is the female remnant of the gubernaculum? male remnant?
Ampulla
Ventral shaft of penis (penile urethra); labia minora
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
External auditory meatus

21. From where does the pulmonary arteries and the ductus arteriosus arise?
Neural crest cells
Neural crest cells
Endometrium
6th aortic arch

22. What results in annular pancreas? How does it happen?
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Endometrium
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3

23. Where is the FGF gene produced? What is it responsible for - How does it do this?
Apical ectodermal ridge; limb lengthening; stimulates mitosis of underlying mesoderm
Mesoderm
Deformation
Fetal and maternal

24. From What embryonic layer are the schwann cells from ?
OCPS and maternal diabetes
Epiblast
Valproate acid
Neural crest cells

25. How many components are there to the placenta? What are they called?
Mesoderm
Amniotic epithelium
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Fetal and maternal

26. Which branchial apparatus makes the external auditory meatus?
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Week 10-12; end of 1st trimester
1st cleft/groove (Ectoderm)
Muscles and arteries

27. What secretes hCG?
DES
2; 1
Muscular ventricular septum; no
Synctiotrophoblast

28. From what region does the cerebral hemisphere form?
Skewed development of AP septum
Telencephalon
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)

29. What are the aspects of fetal alcohol syndrome?
Prosencephalon - mesencephalon - rhombencephalon
Ventral; failure of urogenital folds to close
Mental retardation - holoprosencephaly - facial features - fistulas
Decreased pulmonary resistance in the pulmonary vasculature

30. Gastroschisis is extrusion of abdominal contents out of abdominal folds ___________ by peritoneum
not covered
LH
Mesoderm
Deformation

31. From what aortic arch does the common carotid artery arise? what else arises from this arch?
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells
3rd; proximal part of the internal carotid artery
blood entering the RA
Folate antagonists

32. When does erythropoeisis begin in the bone marow?
Prosencephalon
Foregut; dorsal mesentery (mesodermal)
28 week onward
Endocardial cushions

33. What is a zygote?
Myelencephalon
Day 6; maintains corpus luteum; 1st trimester
Sperm plus egg
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts

34. What artery is derived branchial (aortic) arch 3?
Upper 1/3; urogenital sinus
Polyhydramnios - Down syndrome - Esophageal/duodenal atresia - Imperforate anus - Meckel diverticulum
Ampulla
Common carotid and internal carotid

35. From what branchial derivative do the parafollicular cells arise?
Absent cerebellar vermis; cystic enlargement of 4th ventricle
4th/5th branchial pouches
Excessive resorption of septum primum or secondum (or both)
Dorsal and ventral buds

36. What do the arches of the branchial apparatus correlate to?
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Neural crest cells
Mesdoerm
A vitelline fistula - failure of vitelline duct to close

37. What causes the degeneration of the spinal cord in syringomelia?
Mesoderm
Rostral fold closure ; lateral fold closure; lateral fold closure; caudal fold closure
Neural crest cells
Fluid filled syrinx causes expansion and degeneration of cord tracts

38. What embryological structures give rise to the SVC?
Diencephalon
Mesencephalon
Right common cardinal vein and right anterior cardinal vein
Week 8

39. What trisomy is associated with holoprosencephaly? What teratogen?
Decreased pulmonary resistance in the pulmonary vasculature
Pataus; fetal alcohol syndrome
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Metencephalon; cerebellum

40. What does DHT turn the genital tubercle into? estrogen?
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Nicotine; preterm labor
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)
Week 8

41. What axis does the alar plate form? what neural system does it become?
Left horn of the sinus venosus
Endoderm
Dorsal ventral axis
Dorsal; sensory

42. How is amniontic fluid excreted? How is amniotic fluid resorped?
Maxillary and medial nasal processes
Fetal kidney; fetal swallows - absorbs - and then removed from placental blood
Fetal alcohol syndrome; mental retardation
XII

43. What are the two components of the fetal component of the placenta?
Neural crest cells
Cytotrophoblast and synctiotrophoblast
Surface ectoderm
Endoderm

44. Only _______________________________ are associated with neural tube defects
arnold chiari associated with thoraclumbar myelomeningocele
No more umbilical circulation emptying into RA
Cranio - caudal; segmental
Sperm plus egg

45. The spleen is ____________ in origin and supplied by a foregut artery
Synctiotrophoblast
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts
mesodermal
Ectoderm

46. From What embryonic layer does the epithelial linings of the oral cavity arise?
Cytotrophoblast
Maxillary and medial nasal processes
Surface ectoderm
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)

47. From what region of the brain does the aqueduct form?
During; instrinsic
Germinal matrix hemorrhage
Persistent connection between amniotic cavity and spinal canal; low folic acid
Rhombencephalon

48. What is a syrinx? Where is it found in syringomelia? What is it associated with?
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II
Mesoderm
Hypertrophy of muscularis externis of pylorus; surgical incision
8

49. What does the ureteric bud interact with and What does it induce it to become?
They are the edge of neural plate folding; all over the body
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct
Mesoderm; nucleous pulposos

50. What is the effect of teratogens before week 3?
Diencephalon
All or none
VSD
...