Embryology (GI, Neuro, Renal)

Question 1

Divisions of gut

Answer 1

Foregut - pharynx to duodenum
Midgut - duodenum to transverse colon
Hindgut - transverse colon to rectum

Question 2

Anterior abd. wall defect: rostral fold closure

Answer 2

Sternal defects

Question 3

Anterior abd. wall defect: lateral fold closure

Answer 3

Omphalocele (protrusion with peritoneum), gastroschisis (protrusion without peritoneum)

Question 4

Anterior abd. wall defect: caudal fold closure

Answer 4

Bladder exstrophy

Question 5

Duodenal atresia

Answer 5

Failure to recanalize (seen in Trisomy 21)

Question 6

Jejunal, ileal, colonic atresia

Answer 6

Vascular accident in utero –>apple peel atresia (blind ended prox. jejunum with absence of portion of SB and dorsal mesentery; terminal ileum distal to atresia spiraled around ileocolic vessel)

Question 7

Tracheoesophageal anomalies

Answer 7

Esophageal atresia with distal TEF is most common –>drooling, choking, vomiting with first feeding
Air in stomach and cyanosis (laryngospasm)
H type - fistula alone
EA type - gasless abdomen

Question 8

Congenital pyloric stenosis

Answer 8

Hypertrophy of the pylorus (muscularis mucosa) causes obstruction and palpable “olive” mass in epigastric region
Nonbilious projectile vomiting at ~2 weeks

Question 9

Midgut volvulus

Answer 9

Abnormal rotation and fixation of midgut –>intestinal malrotation –>intestinal obstruction, cecum in RUQ fixed by adhesions (Ladd’s bands)

Question 10

Mesodermal defects: VACTERL

Answer 10

Vertebral abnormalities, anal atresia, cardiac abnormalities, TEF, renal abnormalities, limb abnormalities

Question 11

Pancreas embryology

Answer 11

Derived from foregut; ventral pancreatic bud - part of head, uncinate, main pancreatic duct
Dorsal pancreatic bud - rest of head, body, tail, isthmus, accessory pancreatic duct

Question 12

Annular pancreas

Answer 12

Ventral pancreatic bud abnormally encircles 2nd part of duodenum; forms a ring of pancreas that may cause duodenal narrowing

Question 13

Pancreas divisum

Answer 13

Ventral and dorsal parts fail to fuse at 8 weeks

Question 14

Spleen

Answer 14

Arises in mesentery of stomach but is supplied by foregut

Question 15

Neural plate formation

Answer 15

Notochord induces overlying ectoderm to differentiate into neuroectoderm and form neural plate

Question 16

Neural tube and neural crest cells

Answer 16

Derived from neural plate

Question 17

Divisions of neural plate

Answer 17

Alar plate (dorsal): sensory
Basal plate (ventral): motor

Question 18

Three primary vesicles of developing brain

Answer 18

Forebrain (prosencephalon)
Midbrain (mesoencephalon)
Hindbrain (rhombencephalon)

Question 19

Five secondary vesicles of developing brain: Telencephalon

Answer 19

Telencephalon –>cerebral hemispheres and lateral ventricles

Question 20

Five secondary vesicles of developing brain: Diencephalon

Answer 20

Thalamus and 3rd ventricle

Question 21

Five secondary vesicles of developing brain: Mesencephalon

Answer 21

Midbrain and aqueduct

Question 22

Five secondary vesicles of developing brain: Metencephalon

Answer 22

Pons and cerebellum, upper part of 4th ventricle

Question 23

Five secondary vesicles of developing brain: Myelencephalon

Answer 23

Medulla and lower part of 4th ventricle

Question 24

Neural tube defects

Answer 24

Neuropores fail to fuse in 4th week –> persistent connection between amniotic cavity and spinal canal. Associated with low folic acid intake during and prior to pregnancy

Question 25

Markers for NTDs

Answer 25

Elevated AFP and AChE

Question 26

Spina bifida occulta

Answer 26

Failure of bony canal closure, but no structural herniation and intact dura Seen at lower vertebral levels and assoc. with tuft of hair or skin dimple at site of defect

Question 27

Meningocele

Answer 27

Meninges herniate through spinal canal defect

Question 28

Meningomyelocele

Answer 28

Meninges and spinal cord herniate through spinal canal defect

Question 29

Anencephaly

Answer 29

Malformation of anterior NT resulting in no forebrain, open calvarium Associations: elevated AFP, polyhydramnios, maternal diabetes (type I)

Question 30

Holoprosencephaly

Answer 30

Failure of left and right hemispheres to separate, usually occurs during weeks 5-6. Complete multifactorial etiology that may present as cleft lip/palate or cyclopia

Question 31

Arnold Chiari I

Answer 31

Low lying cerebellar tonsils extend beyond foramen magnum; asymptomatic in infant, associated with adult headaches and ataxia

Question 32

Arnold Chiari II

Answer 32

Significant cerebellar and vermian herniation through foramen magnum with aqueductal stenosis and hydrocephalus. Thoracolumbar myelomeningocele and paralysis below defect.

Question 33

Dandy-Walker

Answer 33

Agenesis of cerebellar vemis with cystic enlargement of 4th ventricle. Associated with hydrocephalus and spina bifida.

Question 34

Syringomyelia

Answer 34

Cystic enlargement of central canal of SC --> anterior white commissure damage Capelike bilateral loss of pain/temp sensation in upper extremities (usu. at C8-T1). Associated with Arnold Chiari I.

Question 35

Tongue development

Answer 35

1st branchial arch forms anterior 2/3rds -- sense via V3, taste via CN VII 3rd branchial arch forms posterior 1/3 -- sense and taste via CN IX, X Motor innervation via CN XII Muscules are derived from occipital myotomes

Question 36

Kidney embryology

Answer 36

Pronephros - develops until week 4 then degenerates Mesonephros - 1st trimester kidney, then contributes to male genital system Metanephros - permanent; appears in 5th week

Question 37

Ureteric bud

Answer 37

Derived from caudal end of mesonephros; gives rise to ureter, pelvises, calyces, collecting ducts

Question 38

Metanephric mesenchyme

Answer 38

Ureteric bud interacts with this tissue; interaction induces differentiation and formation of glomerulus -->DCT Aberrant interactions may result in congenital kidney malformations

Question 39

Ureteropelvic junction

Answer 39

Last area to canalize -->most common site of obstruction (hydronephrosis) in fetus

Question 40

Potter's syndrome

Answer 40

Compression of fetus -->limb deformities, facial deformities, pulmonary hypoplasia May be due to ARPKD, posterior urethral valves, bilateral renal agenesis

Question 41

Horseshoe kidney

Answer 41

Inferior poles of both kidneys fuse and get trapped under IMA during ascent. Associated with Turner syndrome.

Question 42

Multicystic dysplastic kidney

Answer 42

Due to abnormal interaction between ureteric bud and metanephric mesenchyme. Nonfunctioning kidney made of cysts and connective tissue Unilateral -->compensatory hypertrophy of contralateral kidney