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USMLE Embryo

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Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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1. Most myelomeningoceles present in the _______ region
Lithium; valve leaflets attach to domain down low in RV- 'atrialized RV'
80%
lumbosacral
Week 3-8

2. Where is the mothers blood located in the placenta?
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Fetal kidney; fetal swallows - absorbs - and then removed from placental blood
Lacunae in between the chorionic villi
Rhombencephalon

3. From what does bicornuate uterus arise? What is it associated with?
External auditory meatus
Sperm plus egg
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Epiblast

4. Which part of the chorionic villi can make cells?
Cytotrophoblast
Rhombencephalon
septum primum and/or secundum
Yolk sac; 3rd week

5. What does the ductus arteriosus shunt blood away from - to where? What is its remnant?
elevated AFP
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Aortic arch (from left side); right subclavian (on the right)
Tetracyclines

6. Which branchial apparatus develops into the superior parathyroids?
Neural crest cells
4th arch; 6th arch
4th pouch
Endoderm

7. From What embryonic layer do the parafollicular cells of the thyroid arise?
IMA
Endoderm
is no longer intact
Neural crest cells

8. What is a teratogen that causes Ebsteins anomaly? What is ebsteins anomaly?

9. From What embryonic layer are the dorsal root and celiac ganglion from?
Neural crest cells
Neural plate; closes by week 4
DiGeorge
Day 6; with implantation

10. What axis does the basal plate form? what neural system does it become?
Mesonephros; male genital system
Failure of the urachus to obliterate
Ventral ; motor
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum

11. What embryonic structure gives rise to the ascending aorta? what else does it give rise to?
Failure of the urachus to obliterate
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Truncus arteriosus; pulmonary trunk
secondary palate

12. From What embryonic layer do CNS neurons arise?
Congenital and chromosomal abnormalities
Muscles of facial expression - stapedius - stylohyoid - posterior belly of the digastric
Neuroectoderm
Right horn of the SV

13. What is Treacher Collins syndrome? What is the result?
Surface ectoderm
Mesoderm
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)

14. From where does the ureteric bud arise? What does it give rise to?
3rd pouch
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts
Cleft lip/palate

15. What is the effect of teratogens before week 3?
Week 8
Deoxygenated blood; fetal internal iliac arteries to placenta
Sperm plus egg
All or none

16. By what week is there fetal movement?
Meckels cartilage: mandible - malleus - INCUS - sphenoMandibular ligament; CN V2 and V3
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Week 8
Arches 3 and 4

17. As a horseshoe kidney ascends during kidney development - What do they get trapped under?
Endoderm
IMA
Aminoglycosides
Membrane - all 3 from 1st appartus

18. How do adults with annular pancreas present? and At What age?
After; extrinsic
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Lithium; valve leaflets attach to domain down low in RV- 'atrialized RV'
Neural crest migration - they then cause spiral

19. What causes the transposition of the great vessels? What does it result in?
Failure to spiral (aorta coming out of RV and PA coming out of left ventricle)- two completely separate systems
Day 6; with implantation
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Pulm art (prox) and ductus arteriosus

20. What are the three results of having pathology in the aorticopulmonary septum?
Primitive atrium
Week 4
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)
Surface ectoderm

21. Cleft lip is a failure of fusion of ________ and ______.
Maxillary and medial nasal processes
Mesoderm
After; extrinsic
Maxillary

22. What does DHT turn the genital tubercle into? estrogen?
Mesoderm
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Neuroectoderm
Grooves/clefts; arches; pouches

23. Where is sonic hedgehog gene produced? What axis is it responsible in patterning?
OCPS and maternal diabetes
Base of limbs in the zone of polarizing activity; ant - post
VSD
XII

24. What does the first branchial pouch create?
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells
Ampulla
Meckels cartilage: mandible - malleus - INCUS - sphenoMandibular ligament; CN V2 and V3
Outgrowth of mesonephric as ureteric bud; most caudal

25. Where does the blastocyst implant in the uterus? During what phase of the menstrual cycle?
3rd pouch
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch sensation
Post. sup wall; luteal phase

26. What is meckel's diverticulum? What is it associated with? What does that cause?
Excessive resorption of septum primum or secondum (or both)
Ebsteins anomaly; tricuspid atresia
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Ectoderm

27. What are two common findings in pyloric stenosis?
Neuroectoderm
Prostaglandins
Pataus; fetal alcohol syndrome
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks

28. From what region of the brain does the fourth ventricle form?
2nd pouch
Mesoderm; 3 week
Post. sup wall; luteal phase
Rhombencephalon

29. From What embryonic layer does the retina arise?
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
Neuroectoderm
VACTERL; OCPs and maternal diabetes

30. What is the memranous interventricular formaen made from?
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Indomethacin; blocks PG production
Primitive ventricle
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells

31. what happens in hydrocele?
Apical ectodermal ridge
Tunica vaginalis not fully fused
hypospadias
Fetal alcohol syndrome; mental retardation

32. Name a syndrome cleft palate is often seen in
Aortic arch and prox part of subclavian
DiGeorge
Mental retardation - holoprosencephaly - facial features - fistulas
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18

33. What artery is derived branchial (aortic) arch 1?
primary palate
Maxillary
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells
6th aortic arch

34. What artery is derived branchial (aortic) arch 4?
When left to right shunting switching to right to left shunting
Aortic arch and prox part of subclavian
Incomplete; yes
Lithium

35. From what arches are the neural crest cells that form the aorticpulmonary septum derived?
Outgrowth of mesonephric as ureteric bud; most caudal
3 -4 -6
First branchial pouch
Ventral ; motor

36. With the first breath the infant take - pulmonary vasculature resistance _______ which causes an increase in left atrial pressure
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
Prevent recurrent UTIs
Decreases
V3; VII

37. What three layers form during gastrulation? From What do they form? and what week does gastrulation occur?
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
OCPS and maternal diabetes
Prosencephalon - mesencephalon - rhombencephalon
Week 8

38. What is the notochord? What does the notochord later become?
Neural crest cells
Muscles of Mastication: Temporalis - masseter - Lateral and Medila pterygoids - Mylohyoid - anterior belly of the digastric - tensor tympani - tensor veli palatini; ant 2/3 of tongue
Mesoderm; nucleous pulposos
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII

39. What are the two types of posterior fossa malformations? which one results in a hindbrain crowding? and which results in an enlarged posterior fossa? which one is associated with syringomelia?
Lacunae in between the chorionic villi
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain

40. What hormone is hcG structurally similar too?
Week 10-12; end of 1st trimester
hypertrophy
LH
Mesonephros; male genital system

41. What artery is derived branchial (aortic) arch 2?
Fallopian tube - uterus - upper 1/3 of vagina
Left horn of the sinus venosus
Lots - cleft palate/lip
Stapedius and hyoid artery

42. what drug is used to help close a PDA? what else does this drug treat?
Endoderm
arnold chiari associated with thoraclumbar myelomeningocele
Indomethacin; blocks PG production
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus

43. From where does the permanent kidney for? is it most caudal or most cranial?
primary palate
Truncus arteriosus; pulmonary trunk
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
Outgrowth of mesonephric as ureteric bud; most caudal

44. What causes urine discharge from the umbilicus?
Mesoderm
mesodermal
Failure of the urachus to obliterate
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)

45. The notochord is...
Muscles and arteries
mesoderm
Week 4
1st

46. In both meningocele and myelomeningocele the dura...
Neural crest cells
is no longer intact
hypertrophy
Neuroectoderm

47. what muscles are derived from branchial arch 2?
3rd pouch
Neural crest cells
Muscles of facial expression - stapedius - stylohyoid - posterior belly of the digastric
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain

48. Does malformation occur during or after the embryonic period? is it due to an extrinsic or intrinsic disruption?
During; instrinsic
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Allantois
Neural crest cells

49. What teratogen can cause inhibition of intestinal folate absorption and thus neural tube defects?
Germinal matrix hemorrhage
Endoderm
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Valproate acid

50. From What embryonic layer does bone of the skulls arise?
Bones - cartilage - and nerves
Bone/cartilage and nerves
Neuroectoderm
Neural crest cells