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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 two things cause VACTERL syndrome?
Mental retardation - holoprosencephaly - facial features - fistulas
Neuroectoderm
OCPS and maternal diabetes
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)

2. Which CN accounts for the anterior 2/3 of the tongues sensation and pain? how about taste?
V3; VII
can make cells
1st
DiGeorge

3. How many umbilical arteries are there? How many umbilical veins?
Ionizing
Lots - cleft palate/lip
not covered
2; 1

4. What does the foramen ovale shunt blood from - to where? What is its remnant?
From teh lung;blood from IVC in RA to LA; fossa ovalis
80%
Neural crest cells
Ectoderm; endoderm

5. Where is Wnt 7 gene produced?
Dorsal ventral axis
Muscles and arteries
Right horn of the SV
Apical ectodermal ridge

6. As a horseshoe kidney ascends during kidney development - What do they get trapped under?
Endoderm
Bones - cartilage - and nerves
IMA
Maternally derived; meconium

7. Which arches form the posterior 1/3 of the tongue?
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Week 8
LH
Arches 3 and 4

8. When does hCG secretion take place? with what event?
Day 6; with implantation
Decreased pulmonary resistance in the pulmonary vasculature
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Week 8

9. From What embryonic layer does the lens of the eye arise?
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
Surface ectoderm
Week 3-8
Dorsal; sensory

10. Before birth - blood entering the LA is less than...
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum
monoamniotic
blood entering the RA
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen

11. What is perinauds syndrome?
Endoderm
Sonic Hedgehog
Surface ectoderm
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)

12. What is the effect of teratogens after week 8?
Deformation
Persistent connection between amniotic cavity and spinal canal; low folic acid
mesodermal
Turners; inferior

13. What layer is the epiblast? hypoblast?
Endocardial cushions
Obliterated; forms tunica vaginalis
Ectoderm; endoderm
Branchial arch 2

14. From What embryonic layer does the oligodendrocytes arise?
Maxillary and medial nasal processes
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)
Fetal kidney; fetal swallows - absorbs - and then removed from placental blood
Neuroectoderm

15. From where is the allantois formed? During what week?
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
Left horn of the sinus venosus
Respiratory distress syndrome
Yolk sac; 3rd week

16. Which branchial derivative accounts for the sensation and taste in the posterior 2/3 of the tongue? how about the very back?
A vitelline fistula - failure of vitelline duct to close
hypospadias
Apical ectodermal ridge
4th arch; 6th arch

17. what bone/cartilage are derived from branchial arch 4-6?
Occiptal
Maternally derived; meconium
Thyroid - cricoid - arytenoids - corniculate cuneiform
OCPS and maternal diabetes

18. Which branchial derivative accounts for the posterior 2/3 of the tongue?
3rd and 4th arches
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Surface ectoderm
Endoderm

19. How do you differentiate a thyroglossal duct cyst from a persistent cervical sinus?
Endoderm
Prenatal and perinatal
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Mesoderm

20. What is the mnueomonic for the mesodermal defects? What does it stand for?
Mesoderm
8
Tetracyclines
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects

21. Monochorionic - ___________ twins are conjoined
StyloPharyngeus
Deoxygenated blood; fetal internal iliac arteries to placenta
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)
monoamniotic

22. From What embryonic layer does bone arise ?
Mesoderm
Oxygenated; placenta to fetus (IVC)
Fluid filled syrinx causes expansion and degeneration of cord tracts
4th arch; 6th arch

23. What teratogen can cause IUGR and ADHD in a fetus? what else can this teratogen cause?
Deformation
Nicotine; preterm labor
Ampulla
VSD

24. During what week does the heart begin to beat?
Week 4
Pronephros - mesonephros - metanephros; pronephros; most cranially
Neural crest cells
monoamniotic

25. What artery is derived branchial (aortic) arch 2?
Epiblast
Stapedius and hyoid artery
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs

26. During what months is the fetus most susceptible to teratogens? What trimester?
Synctiotrophoblast; outer; no
External auditory meatus
Surface ectoderm
Embryonic period; 1st trimester

27. What is the most common subtype of tracheoesophageal fistula? name some symptoms (hint: O2 levels - feeding - stomach on CXR - - amnios? - NG tube? - respiratory infection? )
Neural crest cells
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct
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
Post. sup wall; luteal phase

28. When is most important to take folic acid to prevent neural tube defects?
Surface ectoderm
Maxillary and medial nasal processes
Day 6; with implantation
Before getting pregnant!

29. When does erythropoeisis begin in the bone marow?
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
DES
28 week onward
Fallopian tube - uterus - upper 1/3 of vagina

30. What embryological structure gives rise to the smooth part of the right atrium?
OCPS and maternal diabetes
Right horn of the SV
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
is no longer intact

31. What does DHT turn the genital tubercle into? estrogen?
Bones - cartilage - and nerves
Hypertrophy of muscularis externis of pylorus; surgical incision
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs

32. From which germlayer does the thyroid develop?? From what structure exactly?
Endoderm - floor of primitive pharynx
Oxygenated; placenta to fetus (IVC)
Right common cardinal vein and right anterior cardinal vein
primary palate

33. Where does fertilization occur?
Neural crest migration - they then cause spiral
Rhombencephalon
Ampulla
Mid gut to yolk sac; omphalomesenteric duct; 7th week

34. Which CN allows for taste and sensation in the posterior 1/3 of the tongue? how about the very back ?
Prosencephalon - mesencephalon - rhombencephalon
...
Polyhydramnios
IX; X

35. What is contained in the umbilical cord?
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus
Week 8
Increase in oxygen concentration which decreases prostaglandin concentration
Decreases

36. What teratogen can cause vaginal clear cell adenocarcinoma in the fetus?
Amniotic cavity and yolk sac
Tunica vaginalis not fully fused
Endoderm
DES

37. What effect does warfarin have on the fetus?
Lithium; valve leaflets attach to domain down low in RV- 'atrialized RV'
Hemorrhage - bone deformities
XII
Lacunae in between the chorionic villi

38. Name a syndrome cleft palate is often seen in
Surface ectoderm
All or none
DiGeorge
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)

39. From what aortic arch does the common carotid artery arise? what else arises from this arch?
3rd; proximal part of the internal carotid artery
Base of limbs in the zone of polarizing activity; ant - post
Common carotid and internal carotid
Stapedius and hyoid artery

40. From What embryonic layer are the melanocytes from?
Neural crest cells
Aminoglycosides
Prostaglandins
Prosencephalon

41. From What embryonic layer do the salivary - sweat and mammary glands arise?
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Neuroectoderm
Surface ectoderm
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)

42. What arises from the fourth aortic arch?
Aortic arch (from left side); right subclavian (on the right)
Prostaglandins
External auditory meatus
Maxillary and medial nasal processes

43. What is used to keep the PDA open?
Neuroectoderm
Muscular ventricular septum; no
Prostaglandins
StyloPharyngeus

44. From What embryonic layer is the kidney and the adrenal cortex from?
Maxillary and medial nasal processes
Neural crest cells
Endocardial cushions
Mesoderm

45. From What embryonic layer does connective tissue and muscle arise?
Decreased pulmonary resistance in the pulmonary vasculature
Mesoderm
Annular pancrease
They are the edge of neural plate folding; all over the body

46. What do the arches of the branchial apparatus correlate to?
Endometrium
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Mesdoerm

47. During what week do the limbs begin to form?
Fetal kidney; fetal swallows - absorbs - and then removed from placental blood
Ionizing
4th/5th branchial pouches
Week 4

48. From what arches are the neural crest cells that form the aorticpulmonary septum derived?
pyloric stenosis
Endometrium
Mesonephros; male genital system
3 -4 -6

49. What is the neural plate and From what does it form?
3rd pouch
Ectoderm
Ventral ; motor
Epiblast

50. What does the mullerian duct develop into? wollffian?
Tunica vaginalis not fully fused
Fallopian tube - uterus - upper 1/3 of vagina
Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch sensation
Neural crest cells