Test your basic knowledge |

USMLE Embryo

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

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 is the homeobox gene responsible in developing? (What axis)
Cranio - caudal; segmental
Mesoderm; nucleous pulposos
Mesoderm
Mesoderm

2. What does the first cleft/groove of the branchial apparatus develop into?
External auditory meatus
Decidual basalis
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
3rd and 4th arches

3. From What embryonic layer is aorticopulmonary septum from ?
After; extrinsic
Neural crest cells
Lithium
Polyhydramnios

4. What effect does warfarin have on the fetus?
Ectoderm; endoderm
Neural crest cells
Hemorrhage - bone deformities
No more umbilical circulation emptying into RA

5. From what are the umbilical arteries and veins derived from?
Urachus/median umbilical ligament; bladder and yolk sac
Allantois
Neural plate; closes by week 4
Annular pancrease

6. What is the Eisenmeger complex?
Hemorrhage - bone deformities
6th aortic arch
Excessive resorption of septum primum or secondum (or both)
When left to right shunting switching to right to left shunting

7. What is the female remnant of the gubernaculum? male remnant?
Oxygenated; placenta to fetus (IVC)
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Ventral bud
Alkylating agents

8. which teratogen can cause Ebsteins anomaly in the fetus?
DES
Decreased pulmonary resistance in the pulmonary vasculature
Decreased separation of hemispheres across midline; cyclopia
Lithium

9. 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?
1st
External auditory meatus
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
pyloric stenosis

10. From What embryonic layer does the epidermis arise?
Surface ectoderm
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Endoderm

11. what bone/cartilage and nerves are derived from branchial arch 3?
Ebsteins anomaly; tricuspid atresia
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Endoderm
Greater horn of hyoid; CN IX (styloPharyngeus)

12. Where is Wnt 7 gene produced?
Lithium
Mesoderm
Apical ectodermal ridge
Aberrant development of 3rd and 4th pouches; t cell def (thymic aplasia) - hypocalcemia (failure of parathyroid development) - CF and CV defects

13. From What embryonic layer does a craniopharygioma arise?
Surface ectoderm
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
3
Embryonic period; 1st trimester

14. From What embryonic layer does the olfactory epithelium arise?
septum primum and/or secundum
Surface ectoderm
Dorsal; faulty positioning of genital tubercle
Primitive ventricle

15. In anencephaly you see...
Week 10-12; end of 1st trimester
elevated AFP
Metencephalon; cerebellum
3rd pouch

16. From where did a branchial cleft cyst arise if it found?
Bulbos Cordis; right ventricle entirely
Week 4; week 3
Found in lateral neck; from no obliteration of 2-4th clefts
Rhombencephalon

17. What artery is derived branchial (aortic) arch 2?
Vascular accident intra uterine; apple peel atresia
From endocardial cushions (ventral and dorsal meet each other)
Stapedius and hyoid artery
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis

18. What does the vitelline duct connect? What is it also known as? when should it obliterate?
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Mid gut to yolk sac; omphalomesenteric duct; 7th week
Post. sup wall; luteal phase
Neural crest cells

19. From What embryonic layer does bone arise ?
Mesonephros; male genital system
Pataus; fetal alcohol syndrome
Congenital and chromosomal abnormalities
Mesoderm

20. 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)
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum
Week 4; week 3

21. From What embryonic layer do the ependymal cells arise?
During; instrinsic
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
Neuroectoderm
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects

22. What does the RET gene encode? what neoplasias is it associated with?
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
can make cells
Decreases
hypertrophy

23. What are the two walls of the prosencephalon and What do they become?
Aortic arch and prox part of subclavian
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
Foregut; dorsal mesentery (mesodermal)
Cerebral hemisphere - thalami

24. Which CN allows for taste and sensation in the posterior 1/3 of the tongue? how about the very back ?
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus
Rhombencephalon
IX; X
When left to right shunting switching to right to left shunting

25. What components do the mesoderm of the branchial arches give rise to?
Muscles and arteries
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)
Mesoderm
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs

26. What is duodenal atresia usually due to? What trisomy is it most often seen in?
Neural crest cells
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Failure to recanalize; 21
secondary palate

27. is epispadias or hypospadias associated with exstrophy of the bladder?
can make cells
Stapedius and hyoid artery
Epispadias
Lots - cleft palate/lip

28. From what arches are the neural crest cells that form the aorticpulmonary septum derived?
Endoderm
3 -4 -6
Endoderm
Occiptal

29. From What embryonic layer are the schwann cells from ?
Primitive atrium
2nd; 2nd
Neural crest cells
Allantois

30. What is the neural plate and From what does it form?
Week 4
6th aortic arch
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Ectoderm

31. What causes a large posterior fossa in a dandy walker malformation? What is found in this fossa?
During; instrinsic
Failure to recanalize; 21
Absent cerebellar vermis; cystic enlargement of 4th ventricle
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs

32. What is an example of a syndrome that can cause abnormal neural crest migration and thus CV abnormalities?
Lots - cleft palate/lip
DiGeorge
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; 3 week

33. From what branchial derivative do the parafollicular cells arise?
Skewed development of AP septum
Muscles of facial expression - stapedius - stylohyoid - posterior belly of the digastric
VSD
4th/5th branchial pouches

34. what chemo drugs can cause neural tube defects in the fetus?
Folate antagonists
Where the epiblast and hypoblast fuse
28 week onward
5th

35. What embryologic structure provides the aorticpulmonary septum?
T neuroectoderm
Neural crest cells
Neural crest migration - they then cause spiral
Neural crest cells

36. What teratogen can cause IUGR and ADHD in a fetus? what else can this teratogen cause?
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
3rd; proximal part of the internal carotid artery
Nicotine; preterm labor
Foregut; dorsal mesentery (mesodermal)

37. What do membranous interventricular septal defect cause? What does this lead to?
Temporary cervical sinus
Initial left to right shunting - then switches
5th
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II

38. At what week does the fetus look like a baby?
3rd; proximal part of the internal carotid artery
Week 8
Neuroectoderm
Week 4

39. What do the groove/clefts of the branchial apparatus correlate to?
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Ectoderm
Truncus arteriosus; pulmonary trunk
Hepatic circulation; ligamentum venosum

40. What is an arnold chiari II malformation? through what hole does it herniate?
Tunica vaginalis not fully fused
Cerebellar tonsillar herniation through foramen magnum
Temporary cervical sinus
Neural crest migration - they then cause spiral

41. How many components are there to the placenta? What are they called?
T neuroectoderm
4th week
Branchial arch 2
Fetal and maternal

42. Gastroschisis is extrusion of abdominal contents out of abdominal folds ___________ by peritoneum
External auditory meatus
Dorsal ventral axis
1st branchial arch
not covered

43. From What embryonic layer does the spinal cord arise?
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II
Neuroectoderm
primary palate
Week 10-12; end of 1st trimester

44. What are two common findings in pyloric stenosis?
secondary palate
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks

45. What happens in pancreas divisum? what results?
During; instrinsic
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
elevated AFP
Week 4; week 3

46. What does DHT turn the labioscrotal swelling into? estrogen?
Scrotum; labia majora
Foregut; dorsal mesentery (mesodermal)
Mesoderm
is no longer intact

47. What artery is derived branchial (aortic) arch 6?
Pulm art (prox) and ductus arteriosus
Apical ectodermal ridge
Fetal alcohol syndrome; mental retardation
Duodenum to transverse colon; distal transverse colon to rectum

48. What is the effect of teratogens after week 8?
External auditory meatus
No organ in each; agenesis no primordial tissue
1st
Deformation

49. What layer is the epiblast? hypoblast?
Ectoderm; endoderm
Neural crest cells
Mental retardation - holoprosencephaly - facial features - fistulas
Ebsteins anomaly; tricuspid atresia

50. What are the two components of the fetal component of the placenta?
Cytotrophoblast and synctiotrophoblast
Mid gut to yolk sac; omphalomesenteric duct; 7th week
Folate antagonists
Week 3-8