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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. From What embryonic layer do the astrocytes arise?
Neuroectoderm
During; instrinsic
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
Failure of bony spinal canal to fuse; no; lower vertebral levels

2. Gastroschisis is extrusion of abdominal contents out of abdominal folds ___________ by peritoneum
not covered
Urachus/median umbilical ligament; bladder and yolk sac
Polyhydramnios
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck

3. From What embryonic layer does the gut tube epithelium arise?
3rd and 4th arches
Surface ectoderm
Hepatic circulation; ligamentum venosum
Endoderm

4. What are the aspects of fetal alcohol syndrome?
Nutrient and gas for exchange; endometrium
Mental retardation - holoprosencephaly - facial features - fistulas
Primitive ventricle
Hemorrhage - bone deformities

5. What trisomy is associated with holoprosencephaly? What teratogen?
Neural crest cells
Pataus; fetal alcohol syndrome
IX; X
Yolk sac; 3rd week

6. What is the prochordal plate?
Excessive resorption of septum primum or secondum (or both)
Where the epiblast and hypoblast fuse
VACTERL; OCPs and maternal diabetes
Right horn of the SV

7. Which parts of the pancreas contribute to the head - uncinate process and main pancreatic duct?
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Excessive resorption of septum primum or secondum (or both)
Ventral; failure of urogenital folds to close
Dorsal and ventral buds

8. _____________is common in 1st born males
pyloric stenosis
Diencephalon
First branchial pouch
Right common cardinal vein and right anterior cardinal vein

9. What is the most common autopsy finding in brains of premature infants?
Germinal matrix hemorrhage
primary palate
Failure of the urachus to obliterate; outpouching of the bladder
Mesoderm; 3 week

10. What two things cause VACTERL syndrome?
Cerebellar tonsillar herniation through foramen magnum
OCPS and maternal diabetes
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Mental retardation - holoprosencephaly - facial features - fistulas

11. From what region does the midbrain form from?
Mesencephalon
Endometrium
Bone/cartilage and nerves
Endocardial cushions

12. In both meningocele and myelomeningocele the dura...
...
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Alkylating agents
is no longer intact

13. which teratogen can cause Ebsteins anomaly in the fetus?
Surface ectoderm
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Dorsal; sensory
Lithium

14. From What embryonic layer does the adenohypophysis arise?
Endoderm - floor of primitive pharynx
Surface ectoderm
Respiratory distress syndrome
Ionizing

15. Before birth - blood entering the LA is less than...
blood entering the RA
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Nutrient and gas exchange
Neuroectoderm

16. In what chromosomal disorder is horseshoe kidney commonly seen? what poles of the kidneys fuse?
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Vascular accident intra uterine; apple peel atresia
Neuroectoderm
Turners; inferior

17. Which CN accounts for the anterior 2/3 of the tongues sensation and pain? how about taste?
V3; VII
5th
Mesoderm
Left horn of the sinus venosus

18. How do adults with annular pancreas present? and At What age?
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Left horn of the sinus venosus
Mesdoerm
After; extrinsic

19. What is associated with only one umbilical artery?
Scrotum; labia majora
Congenital and chromosomal abnormalities
Indomethacin; blocks PG production
Neural crest cells

20. What teratogen can cause vaginal clear cell adenocarcinoma in the fetus?
LH
3rd pouch
DES
No more umbilical circulation emptying into RA

21. What congenital abnormality forms a 'double bubble' on xray?
Arnold chiari; syringomyelia
Muscles of facial expression - stapedius - stylohyoid - posterior belly of the digastric
Myelencephalon
Annular pancrease

22. Weeks _______ erythropoiesis takes place in the liver
Where the epiblast and hypoblast fuse
StyloPharyngeus
6-30
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)

23. From What embryonic layer are the schwann cells from ?
Neural crest cells
2nd pouch
mesoderm
can make cells

24. What role does the placenta have?
Nutrient and gas exchange
Fluid filled syrinx causes expansion and degeneration of cord tracts
DHT; estrogen
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari

25. What are markers for neural tube defects in the amniotic cavity? CSF?
Increased AFP and acetycholinesterase (not ACh!) in CSF
Week 8
Decreased pulmonary resistance in the pulmonary vasculature
Bulbourethral glands (of Cowper) and Prostate gland; greater vestibular glands (of Bartholin) and Urethral and paraurethral glands (of Skene)

26. what week do the genitalia start to have male/female characteristics? What trimester is that?
5th
Week 10-12; end of 1st trimester
Prosencephalon - mesencephalon - rhombencephalon
Neural crest migration - they then cause spiral

27. How many components are there to the placenta? What are they called?
Physiologic incomplete muscular ventricular septum
secondary palate
No more umbilical circulation emptying into RA
Fetal and maternal

28. Where is Wnt 7 gene produced?
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Apical ectodermal ridge
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks
Congenital and chromosomal abnormalities

29. What three components make up the branchial/pharyngeal apparatus?
Initial left to right shunting - then switches
Grooves/clefts; arches; pouches
Endoderm
Mesoderm

30. What three layers form during gastrulation? From What do they form? and what week does gastrulation occur?
IMA
3rd pouch
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
Germinal matrix hemorrhage

31. From what aortic arch does the first part of the maxillary artery arise?
First branchial pouch
Endoderm
1st
Thalidomide; nausea

32. From What embryonic layer does the epidermis arise?
Nutrient and gas for exchange; endometrium
Surface ectoderm
Neuroectoderm
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont

33. What is omphalocele? In What trisomies is it seen?
Arnold chiari; syringomyelia
Ventral shaft of penis (penile urethra); labia minora
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18
Spinothalamic first

34. With the first breath the infant take - pulmonary vasculature resistance _______ which causes an increase in left atrial pressure
80%
Decreases
Upper 1/3; urogenital sinus
Dorsal; faulty positioning of genital tubercle

35. From What embryonic layer are the cardiovascular - lymphatics and blood from?
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Mesoderm
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Metencephalon; cerebellum

36. From What embryonic layer do the parafollicular cells of the thyroid arise?
Neural crest cells
Neuroectoderm
Bones - cartilage - and nerves
DES

37. Which branchial apparatus makes the external auditory meatus?
Mesencephalon
Decidual basalis
Week 3; primitive streak formation from the epiblast makes the three layers
1st cleft/groove (Ectoderm)

38. Which part of pancreas contribute to body? tail? isthmus? accessory pancreatic duct?
Ventral bud
Fallopian tube - uterus - upper 1/3 of vagina
Ebsteins anomaly; tricuspid atresia
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs

39. What are the two components of the placenta? From What do they form? which one secreted hcG?
...
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18
Foregut; dorsal mesentery (mesodermal)
Amniotic epithelium

40. which genital embryology is default? From what duct? what duct degenerates without signal to stay?
Female; paramesonephric; mesonephric
Midgut; 10th week
Failure to recanalize; 21
Decreases

41. What type of radiation is teratogenic ?
Ionizing
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II
Left horn of the sinus venosus
2nd; 2nd

42. What do the 2nd through 4th clefts of the branchial apparatus correlate to?
DiGeorge
Temporary cervical sinus
Partial AP septum development; one large vessel leaves the heart - Right to left shunt
Spinothalamic first

43. The inner layer of the chorionic villi...
Amniotic cavity and yolk sac
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)
can make cells
Surface ectoderm

44. What is annular pancreas associated with in infants?
Polyhydramnios - Down syndrome - Esophageal/duodenal atresia - Imperforate anus - Meckel diverticulum
Day 6; with implantation
Week 2; bilaminar disk; epiblast and hypoblast
StyloPharyngeus

45. what bone/cartilage are derived from branchial arch 4-6?
Obliterated; forms tunica vaginalis
Arnold chiari; syringomyelia
Thyroid - cricoid - arytenoids - corniculate cuneiform
Cleft lip/palate

46. What hormones are in charge of external genitalia development in the fetus? (in both male and female)
DHT; estrogen
All 3
Outgrowth of mesonephric as ureteric bud; most caudal
Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch sensation

47. What is a syrinx? Where is it found in syringomelia? What is it associated with?
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II
Dorsal ventral axis
Ectoderm
Failure of bony spinal canal to fuse; no; lower vertebral levels

48. What is perinauds syndrome?
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
Neural crest cells
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Yolk sac; 3rd week

49. What are the two walls of the prosencephalon and What do they become?
3rd pouch
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Renal artery stenosis;
Cerebral hemisphere - thalami

50. Does malformation occur during or after the embryonic period? is it due to an extrinsic or intrinsic disruption?
3rd and 4th arches
5th
During; instrinsic
Medial palatine processes