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 teratogen can cause IUGR and ADHD in a fetus? what else can this teratogen cause?
All or none
Grooves/clefts; arches; pouches
Vascular accident intra uterine; apple peel atresia
Nicotine; preterm labor

2. From What embryonic layer does the adenohypophysis arise?
Surface ectoderm
Female; paramesonephric; mesonephric
Physiologic incomplete muscular ventricular septum
Endoderm

3. When does erythropoeisis begin in the bone marow?
Pronephros - mesonephros - metanephros; pronephros; most cranially
Obliterated; forms tunica vaginalis
Week 4; week 3
28 week onward

4. Where is sonic hedgehog gene produced? What axis is it responsible in patterning?
Pulm art (prox) and ductus arteriosus
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
Base of limbs in the zone of polarizing activity; ant - post
Dorsal ventral axis

5. What do the arches of the branchial apparatus correlate to?
Mesdoerm
Endoderm
Mesencephalon
Mid gut to yolk sac; omphalomesenteric duct; 7th week

6. What axis is Wnt 7 responsible for developing?
Dorsal ventral axis
DES
Fetal and maternal
hypospadias

7. From what region does the midbrain form from?
Fetal alcohol syndrome; mental retardation
Ectoderm
Mesencephalon
Sperm plus egg

8. From What embryonic layer does the sensory organs of the ear arise?
Surface ectoderm
Week 8
Ventral; failure of urogenital folds to close
Pulm art (prox) and ductus arteriosus

9. From What embryonic layer does a craniopharygioma arise?
Surface ectoderm
Week 3; primitive streak formation from the epiblast makes the three layers
Mesencephalon
Prosencephalon

10. What two cavities also form during the second week?
elevated AFP
Scrotum; labia majora
Amniotic cavity and yolk sac
Mesoderm

11. What do membranous interventricular septal defect cause? What does this lead to?
Initial left to right shunting - then switches
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum
Partial closure of vitelline duct so that the patent portion is attached to ileum; ectopic gastric mucosa; melena and periumbilical pain
Stapedius and hyoid artery

12. what muscles are derived from branchial arch 6? CN?
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Lithium
hypertrophy
Week 8

13. What is the fate of the cervical sinuses that develop from the 2nd -4th branchial grooves?
Nutrient and gas for exchange; endometrium
Obliterated
SRY gene on Y chromosomes; sertoli and leydi; MIF and androgens; suppression of paramesonephric ducts and dev. of mesonephric (all respectively)
Amniotic epithelium

14. From What embryonic layer does the olfactory epithelium arise?
Surface ectoderm
V3; VII
secondary palate
They are the edge of neural plate folding; all over the body

15. From What embryonic layer does the pineal gland arise?
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Week 4
OCPS and maternal diabetes
Neuroectoderm

16. What day is the chorion formed?
3
Respiratory distress syndrome
Failure of bony spinal canal to fuse; no; lower vertebral levels
Surface ectoderm

17. Does deformation occur during or after the embryonic period? is it due to an extrinsic or intrinsic disruption?
Blastocyst; epiblast and hypoblast; synctiotrophoblast and cytotrophoblast
Duodenum to transverse colon; distal transverse colon to rectum
After; extrinsic
Mesoderm

18. What layer is the epiblast? hypoblast?
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
Female; paramesonephric; mesonephric
Ectoderm; endoderm
Embryonic period; 1st trimester

19. What embryological structure gives rise to the trabeculated part of the left and right atrium?
arnold chiari associated with thoraclumbar myelomeningocele
OCPS and maternal diabetes
Primitive atrium
Sonic Hedgehog

20. What axis does the alar plate form? what neural system does it become?
Metencephalon; cerebellum
Maxillary
Embryonic period; 1st trimester
Dorsal; sensory

21. Gastroschisis is extrusion of abdominal contents out of abdominal folds ___________ by peritoneum
Polyhydramnios
Apical ectodermal ridge; limb lengthening; stimulates mitosis of underlying mesoderm
not covered
Neural crest cells

22. What does DHT turn the urogenital folds into? estrogen?
Aminoglycosides
Rostral fold closure ; lateral fold closure; lateral fold closure; caudal fold closure
Ventral shaft of penis (penile urethra); labia minora
Right horn of the SV

23. What hormones are in charge of external genitalia development in the fetus? (in both male and female)
Bone/cartilage and nerves
4th pouch
Telencephalon
DHT; estrogen

24. Which branchial derivative accounts for the posterior 2/3 of the tongue?
3rd and 4th arches
Physiologic incomplete muscular ventricular septum
First branchial pouch
Aortic arch and prox part of subclavian

25. failure to close of what fold results in sternal defects? omphalocele? gastrochisis? bladder extrosphy?
Rostral fold closure ; lateral fold closure; lateral fold closure; caudal fold closure
Diencephalon
Week 3-8
Neural crest cells

26. Other than not having a brain - what else is a symptom of anencephaly? why? hint: think about amniotic fluid
Female; paramesonephric; mesonephric
Polyhydramnios
They are the edge of neural plate folding; all over the body
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)

27. What results in annular pancreas? How does it happen?
Tongue
Hypertrophy of muscularis externis of pylorus; surgical incision
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Apical ectodermal ridge

28. what muscles are derived from branchial arch 1?
Ventral; failure of urogenital folds to close
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
3rd; proximal part of the internal carotid artery
Lacunae in between the chorionic villi

29. What is the most common subtype of tracheoesophageal fistula? name some symptoms (hint: O2 levels - feeding - stomach on CXR - - amnios? - NG tube? - respiratory infection? )
...
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
Ectoderm
...

30. What are the aspects of fetal alcohol syndrome?
Ampulla
Neuroectoderm
Mental retardation - holoprosencephaly - facial features - fistulas
Epiblast

31. From What embryonic layer does the epidermis arise?
Arnold chiari; syringomyelia
Surface ectoderm
Mesonephros; male genital system
After; extrinsic

32. WithIn what week does gastrulation occur? What is gastrulation?
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)
Week 4
Endoderm
Week 3; primitive streak formation from the epiblast makes the three layers

33. During what week does the heart begin to beat?
DHT; estrogen
6-30
Week 4
Hepatic circulation; ligamentum venosum

34. How many components are there to the placenta? What are they called?
Persistent connection between amniotic cavity and spinal canal; low folic acid
Surface ectoderm
Fetal and maternal
Week 3-8

35. What gene is produced in the zone of polarizing activity?
2; 1
Sonic Hedgehog
mesoderm
Dorsal; faulty positioning of genital tubercle

36. From where does the medulla form?
When left to right shunting switching to right to left shunting
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts
...
Myelencephalon

37. How is amniontic fluid excreted? How is amniotic fluid resorped?
Aberrant development of 3rd and 4th pouches; t cell def (thymic aplasia) - hypocalcemia (failure of parathyroid development) - CF and CV defects
1st
Fetal alcohol syndrome; mental retardation
Fetal kidney; fetal swallows - absorbs - and then removed from placental blood

38. From where does the ureteric bud arise? What does it give rise to?
Tongue
Myelencephalon
The caudal end mesonephros; the ureter - pelvis - calyces - collecting ducts
Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch sensation

39. Which branchial derivative creates the middle ear cavity - eustachian tube and mastoid air cells?
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Mesoderm
Nutrient and gas for exchange; endometrium
First branchial pouch

40. From What embryonic layer are the dorsal root and celiac ganglion from?
Neural crest cells
Foramen cecum and terminal sulus
IX; X
mesoderm

41. In order to survive tricuspid atresia - What do you need?
Endoderm
VSD
Lithium
Aortic arch and prox part of subclavian

42. which teratogen can cause Ebsteins anomaly in the fetus?
Skewed development of AP septum
Lithium
Mesoderm
Excessive resorption of septum primum or secondum (or both)

43. What type of radiation is teratogenic ?
Umbilical - midgut herniates through umbilical ring; SMA
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
Ionizing

44. Which branchial apparatus develops into the inferior parathyroids?
3rd pouch
Nutrient and gas for exchange; endometrium
80%
Base of limbs in the zone of polarizing activity; ant - post

45. What causes tetralogy of Fallot?
During; instrinsic
Skewed development of AP septum
pyloric stenosis
Pulm art (prox) and ductus arteriosus

46. Name two endocardial cushion defects.
elevated AFP
lumbosacral
Ebsteins anomaly; tricuspid atresia
Oligohydramnios

47. From which branchial derivative does the anterior 2/3 of the tongue develop?
External auditory meatus
Failure of the urachus to obliterate; outpouching of the bladder
hypertrophy
1st branchial arch

48. What is associated with only one umbilical artery?
Congenital and chromosomal abnormalities
Deoxygenated blood; fetal internal iliac arteries to placenta
Neural crest cells
Surface ectoderm

49. During what periods do the damages that cerebral palsy causes occur?
Decreases
Endoderm
Prenatal and perinatal
Neural crest cells

50. What does DHT turn the genital tubercle into? estrogen?
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Scrotum; labia majora
Endoderm
Neural plate; closes by week 4