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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 chemo drugs can cause neural tube defects in the fetus?
Epispadias
Folate antagonists
Neuroectoderm
Spinothalamic first

2. What embryologic structure gives rise to the smooth outflow tracts of the ventricles? what else does it give rise to?
Nutrient and gas exchange
Bulbos Cordis; right ventricle entirely
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)
Scrotum; labia majora

3. Which branchial apparatus derivative makes the tympanic membrane of the ear?
Decreased pulmonary resistance in the pulmonary vasculature
Neural crest cells
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Membrane - all 3 from 1st appartus

4. What axis is Wnt 7 responsible for developing?
Folate antagonists
Dorsal ventral axis
Epiblast
Maxillary and medial nasal processes

5. From what does bicornuate uterus arise? What is it associated with?
Epispadias
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Yolk sac; 3rd week
Tongue

6. Monochorionic - ___________ twins are conjoined
elevated AFP
DiGeorge
Hepatic circulation; ligamentum venosum
monoamniotic

7. From What embryonic layer does the thyroid follicular cells arise?
Ampulla
Endoderm
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
Neuroectoderm

8. What is the defect in spina bifida occulta? is there any structural herniation? where on the spinal cord is it usually seen?
Failure of bony spinal canal to fuse; no; lower vertebral levels
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Pulm art (prox) and ductus arteriosus
is no longer intact

9. To what germ layer does the branchial pouches correlate to?
Neuroectoderm
Endoderm
Right horn of the SV
Embryonic period; 1st trimester

10. What does the maternal component of the placenta provide? Where is it derived from?
Nutrient and gas for exchange; endometrium
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
Sonic Hedgehog
6th aortic arch

11. What is the initial step to interventricular septum development? is it complete?
Neural crest cells
Neuroectoderm
Muscular ventricular septum; no
Amniotic epithelium

12. From What embryonic layer do the ependymal cells arise?
Membrane - all 3 from 1st appartus
Neuroectoderm
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Rhombencephalon

13. From What embryonic layer does the gut tube derivatives arise (lungs liver - pancreas - parathryroid - thyroid follicular cells - thymus)?
Endoderm
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
hypertrophy
Mesoderm

14. Name a syndrome cleft palate is often seen in
DiGeorge
Medial palatine processes
Left horn of the sinus venosus
hypospadias

15. What components do the mesoderm of the branchial arches give rise to?
Muscles and arteries
Ventral bud
Folate antagonists
Neural crest cells

16. which teratogen can cause Ebsteins anomaly in the fetus?
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Primitive ventricle
Lithium
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells

17. What causes persistent Truncus Arteriosus? What does it result in?
Ectoderm; endoderm
Initial left to right shunting - then switches
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Primitive atrium

18. What is omphalocele? In What trisomies is it seen?
Rhombencephalon
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Amniotic epithelium

19. what drug is used to help close a PDA? what else does this drug treat?
Week 8
Mesoderm
Ionizing
Indomethacin; blocks PG production

20. what muscles are derived from branchial arch 6? CN?
Synctiotrophoblast; outer; no
Nutrient and gas exchange
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Arches 3 and 4

21. What does DHT turn the urogenital sinus into? estrogen?
Synctiotrophoblast; outer; no
Increase in oxygen concentration which decreases prostaglandin concentration
Branchial arch 2
Bulbourethral glands (of Cowper) and Prostate gland; greater vestibular glands (of Bartholin) and Urethral and paraurethral glands (of Skene)

22. Where is the apical ectodermal ridge?
Mesoderm
Surface ectoderm
From endocardial cushions (ventral and dorsal meet each other)
Thickened ectoderm at end of each developing limb

23. What is another name for the mesonephric duct? paramesonephric?
Ventral shaft of penis (penile urethra); labia minora
Wolffian; mullerian
Physiologic incomplete muscular ventricular septum
IX; X

24. What is meckel's diverticulum? What is it associated with? What does that cause?
From teh lung;blood from IVC in RA to LA; fossa ovalis
Deoxygenated blood; fetal internal iliac arteries to placenta
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Dorsal; sensory

25. What produces testis determining factor? what cells are produced from this? and What do they secrete? does this result in?
SRY gene on Y chromosomes; sertoli and leydi; MIF and androgens; suppression of paramesonephric ducts and dev. of mesonephric (all respectively)
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Prosencephalon
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects

26. From what arches are the neural crest cells that form the aorticpulmonary septum derived?
3 -4 -6
not covered
Nicotine; preterm labor
Absent cerebellar vermis; cystic enlargement of 4th ventricle

27. What is the primitive streak? From what layer does it form?
Right horn of the SV
Amniotic epithelium
Neural crest migration - they then cause spiral
Mesoderm; epiblast

28. The notochord is...
Increase in oxygen concentration which decreases prostaglandin concentration
mesoderm
Maternally derived; meconium
Right horn of the SV

29. From What do the embryoblast and trophoblast form from? What does the embryoblast split into? the trophoblast?
Grooves/clefts; arches; pouches
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Mesoderm
Neuroectoderm

30. What does the mullerian duct develop into? wollffian?
arnold chiari associated with thoraclumbar myelomeningocele
Common carotid and internal carotid
Fallopian tube - uterus - upper 1/3 of vagina
Aortic arch and prox part of subclavian

31. From What embryonic layer does the neurohypophysis arise?
Endoderm
Pataus; fetal alcohol syndrome
Cytotrophoblast and synctiotrophoblast
Neuroectoderm

32. From What embryonic lare are the odontoblasts from?
Surface ectoderm
SRY gene on Y chromosomes; sertoli and leydi; MIF and androgens; suppression of paramesonephric ducts and dev. of mesonephric (all respectively)
Neural crest cells
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction

33. What teratogen can cause IUGR and ADHD in a fetus? what else can this teratogen cause?
Nicotine; preterm labor
Embryonic period; 1st trimester
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
Polyhydramnios

34. From where does the ureteric bud arise? What does it give rise to?
Skewed development of AP septum
Prevent recurrent UTIs
Prenatal and perinatal
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts

35. Which part of the branchial apparatus makes up membranes?
8
All 3
Increased AFP and acetycholinesterase (not ACh!) in CSF
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck

36. What separates the ant 1/3 and post 2/3 of tongue?
Foramen cecum and terminal sulus
T neuroectoderm
Endoderm
A vitelline fistula - failure of vitelline duct to close

37. From where is the allantois formed? During what week?
Mid gut to yolk sac; omphalomesenteric duct; 7th week
Yolk sac; 3rd week
Neural crest cells
Telencephalon

38. What congenital abnormality forms a 'double bubble' on xray?
Oligohydramnios
Annular pancrease
Aortic arch (from left side); right subclavian (on the right)
Before getting pregnant!

39. Where is the decidua basalis derived from?
Dorsal; sensory
Endometrium
pyloric stenosis
Neuroectoderm

40. When does hcG get secreted? What does it do?up until when ?
Day 6; maintains corpus luteum; 1st trimester
Obliterated; forms tunica vaginalis
From endocardial cushions (ventral and dorsal meet each other)
lumbosacral

41. What is germinal matrix hemorrhage associated with?
ACE inhibitors - HCTZ
SRY gene on Y chromosomes; sertoli and leydi; MIF and androgens; suppression of paramesonephric ducts and dev. of mesonephric (all respectively)
Respiratory distress syndrome
T neuroectoderm

42. From where is amniotic fluid produced? other than electrolytes and carbs - what else does it contain?
Maternally derived; meconium
Neuroectoderm
Obliterated
Ampulla

43. Which branchial arch derivative is obliterated?
5th
Surface ectoderm
Allantois
Initial left to right shunting - then switches

44. Which branchial derivative accounts for taste in the ant 2/3?
Polyhydramnios
Branchial arch 2
is no longer intact
Neural crest cells

45. What artery is derived branchial (aortic) arch 4?
Skewed development of AP septum
Annular pancrease
Neural crest cells
Aortic arch and prox part of subclavian

46. During what months is the fetus most susceptible to teratogens? What trimester?
Embryonic period; 1st trimester
Week 8
Mesoderm
Synctiotrophoblast; outer; no

47. In anencephaly you see...
Mesoderm
Neural crest cells
elevated AFP
Sonic Hedgehog

48. From where does pons form from? what else forms from there?
Metencephalon; cerebellum
Day 6; with implantation
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Membrane - all 3 from 1st appartus

49. During what periods do the damages that cerebral palsy causes occur?
Prenatal and perinatal
DiGeorge
V3; VII
OCPS and maternal diabetes

50. From where does the medulla form?
4th week
Myelencephalon
Mid gut to yolk sac; omphalomesenteric duct; 7th week
Surface ectoderm