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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 is DiGeorge syndrome and What does it result in?
Ampulla
Aberrant development of 3rd and 4th pouches; t cell def (thymic aplasia) - hypocalcemia (failure of parathyroid development) - CF and CV defects
Hemorrhage - bone deformities
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts

2. What are two common findings in pyloric stenosis?
Failure of the urachus to obliterate
Membrane - all 3 from 1st appartus
4th arch; 6th arch
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks

3. What type of - amnios does bilateral agenesis form? What three symptoms does this cause?
Mesonephros; male genital system
Hemorrhage - bone deformities
Oligohydramnios
4th/5th branchial pouches

4. What do membranous interventricular septal defect cause? What does this lead to?
Foregut; dorsal mesentery (mesodermal)
Thyroid - cricoid - arytenoids - corniculate cuneiform
Surface ectoderm
Initial left to right shunting - then switches

5. What artery is derived branchial (aortic) arch 6?
Neuroectoderm
Pulm art (prox) and ductus arteriosus
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Prevent recurrent UTIs

6. Pyloric stenosis is characterized by _____________ of muscularis externis in the sphincter
Lots - cleft palate/lip
Aortic arch (from left side); right subclavian (on the right)
hypertrophy
Week 8

7. From What embryonic layer does the gut tube epithelium arise?
Endoderm
Surface ectoderm
They are the edge of neural plate folding; all over the body
Rostral fold closure ; lateral fold closure; lateral fold closure; caudal fold closure

8. Where is Wnt 7 gene produced?
Cleft lip/palate
Endoderm
Apical ectodermal ridge
LH

9. Which branchial derivative accounts for the posterior 2/3 of the tongue?
No organ in each; agenesis no primordial tissue
Endoderm
Mental retardation - holoprosencephaly - facial features - fistulas
3rd and 4th arches

10. Which is more common - epispadias or hypospadias?
Apical ectodermal ridge; limb lengthening; stimulates mitosis of underlying mesoderm
Hypospadias
Embryonic period; 1st trimester
Muscular ventricular septum; no

11. What is the difference between agenesis and aplasia?
No organ in each; agenesis no primordial tissue
Endoderm
Maternally derived; meconium
Renal artery stenosis;

12. What embryologic structure gives rise to the smooth outflow tracts of the ventricles? what else does it give rise to?
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Bulbos Cordis; right ventricle entirely
Incomplete; yes

13. What separated myometrium of the uterus from the blastocyst?
Where the epiblast and hypoblast fuse
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Decidual basalis

14. what chemo drugs can cause neural tube defects in the fetus?
Folate antagonists
Endoderm
septum primum and/or secundum
Ectoderm; endoderm

15. what bone/cartilage are derived from branchial arch 4-6?
Thyroid - cricoid - arytenoids - corniculate cuneiform
Mesdoerm
Endometrium
Mesoderm

16. From What embryonic layer are the schwann cells from ?
Ventral bud
Neuroectoderm
Neural crest cells
When left to right shunting switching to right to left shunting

17. What embryonic structure gives rise to the ascending aorta? what else does it give rise to?
Nicotine; preterm labor
All 3
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
Truncus arteriosus; pulmonary trunk

18. What layer is the epiblast? hypoblast?
Aberrant development of 3rd and 4th pouches; t cell def (thymic aplasia) - hypocalcemia (failure of parathyroid development) - CF and CV defects
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Endoderm - floor of primitive pharynx
Ectoderm; endoderm

19. _____________is common in 1st born males
pyloric stenosis
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Pulm art (prox) and ductus arteriosus
Mesoderm

20. From what aortic arch does the common carotid artery arise? what else arises from this arch?
3rd; proximal part of the internal carotid artery
Neural crest cells
Mesoderm
Stapedius and hyoid artery

21. What does the ductus arteriosus shunt blood away from - to where? What is its remnant?
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Prosencephalon
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Folate antagonists

22. what bone/cartilage and nerves are derived from branchial arch 2?
Arches 3 and 4
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Apical ectodermal ridge
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII

23. What embryological structure gives rise to the trabeculated parts of the left and right ventricle?
Failure to recanalize; 21
Primitive ventricle
IX; X
Prenatal and perinatal

24. What is meckel's diverticulum? What is it associated with? What does that cause?
Ventral; failure of urogenital folds to close
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Nicotine; preterm labor

25. What type of radiation is teratogenic ?
Ionizing
Increased AFP and acetycholinesterase (not ACh!) in CSF
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Nutrient and gas for exchange; endometrium

26. What components do the mesoderm of the branchial arches give rise to?
3rd pouch
secondary palate
arnold chiari associated with thoraclumbar myelomeningocele
Muscles and arteries

27. From What embryonic layer is the spleen from?
Mesoderm
septum primum and/or secundum
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Outgrowth of mesonephric as ureteric bud; most caudal

28. What causes persistent Truncus Arteriosus? What does it result in?
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Mesoderm
During; instrinsic
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells

29. What is the mnueomonic for the mesodermal defects? What does it stand for?
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Oxygenated; placenta to fetus (IVC)
Tetracyclines
Day 6; maintains corpus luteum; 1st trimester

30. What is the effect of teratogens after week 8?
Ventral bud
Maternally derived; meconium
Deformation
Partial AP septum development; one large vessel leaves the heart - Right to left shunt

31. is epispadias or hypospadias associated with exstrophy of the bladder?
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Epispadias
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Turners; inferior

32. During what periods do the damages that cerebral palsy causes occur?
Prenatal and perinatal
Pronephros - mesonephros - metanephros; pronephros; most cranially
3rd; proximal part of the internal carotid artery
Sonic Hedgehog

33. From where do the three different kidneys come from? Which is the earliest one? is it located most cranially or caudally?
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
Pronephros - mesonephros - metanephros; pronephros; most cranially
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
Incomplete; yes

34. What hormones are in charge of external genitalia development in the fetus? (in both male and female)
Sperm plus egg
DHT; estrogen
Week 4; week 3
Urachus/median umbilical ligament; bladder and yolk sac

35. What does the mullerian duct develop into? wollffian?
Incomplete; yes
Fallopian tube - uterus - upper 1/3 of vagina
...
LH

36. Monochorionic - ___________ twins are conjoined
Mesoderm
Ionizing
monoamniotic
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

37. From What embryonic layer are the melanocytes from?
Turners; inferior
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Arnold chiari; syringomyelia
Neural crest cells

38. The notochord is...
Ectoderm
mesoderm
Endocardial cushions
Week 4

39. How do you differentiate a thyroglossal duct cyst from a persistent cervical sinus?
Neuroectoderm
Dorsal; faulty positioning of genital tubercle
Endoderm
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont

40. For what reason do hypospadias need to be fixed?
28 week onward
SRY gene on Y chromosomes; sertoli and leydi; MIF and androgens; suppression of paramesonephric ducts and dev. of mesonephric (all respectively)
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
Prevent recurrent UTIs

41. How many components are there to the placenta? What are they called?
Before getting pregnant!
Aminoglycosides
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Fetal and maternal

42. The inner layer of the chorionic villi...
IX; X
can make cells
Prosencephalon - mesencephalon - rhombencephalon
Thyroid - cricoid - arytenoids - corniculate cuneiform

43. From what aortic arch does the stapedial artery arise? the hyoid?
No more umbilical circulation emptying into RA
Congenital and chromosomal abnormalities
2nd; 2nd
DiGeorge

44. What separates the ant 1/3 and post 2/3 of tongue?
...
5th
Foramen cecum and terminal sulus
monoamniotic

45. What is the kidney that functions at the interim kidney in the 1st trimester? What does it later contribute to?
Mesonephros; male genital system
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
28 week onward
Rhombencephalon

46. What is perinauds syndrome?
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
monoamniotic
V3; VII
2; 1

47. In order to survive tricuspid atresia - What do you need?
A vitelline fistula - failure of vitelline duct to close
VSD
Left horn of the sinus venosus
Allantois

48. What artery is derived branchial (aortic) arch 1?
Pulm art (prox) and ductus arteriosus
Maxillary
Metencephalon; cerebellum
3rd pouch

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

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50. From what region of the brain does the aqueduct form?
Fallopian tube - uterus - upper 1/3 of vagina
Neural plate; closes by week 4
Mesoderm; nucleous pulposos
Rhombencephalon