GI Embryology

Question 1

peritoneum is formed from

Answer 1

mesoderm

Question 2

when is primitive gut tube formed

Answer 2

week 4

Question 3

where is primitive gut tube formed from

Answer 3

top of yolk sac

Question 4

how does the embryo fold to form gut tube

Answer 4

cranially-caudally and laterally

Question 5

gut tube is formed from

Answer 5

yolk sac endoderm

Question 6

what happens along with gut tube formation

Answer 6

body cavity and anterolateral body wall are formed, amnion encases embryo

Question 7

epithelial lining of gut tube is formed from

Answer 7

endoderm

Question 8

all layers of gut tube wall except epithelial lining are formed from

Answer 8

mesoderm

Question 9

path of unpaired aortic branches in embryo

Answer 9

travel from posterior body wall to to gut tube through dorsal mesentery

Question 10

where is gut tube suspended from

Answer 10

posterior body wall

Question 11

what suspends gut tube from posterior body wall

Answer 11

dorsal mesentery

Question 12

where does the liver bud off into

Answer 12

ventral mesentery

Question 13

spleen develops from

Answer 13

mesoderm in dorsal mesentery of stomach

Question 14

rotation of the stomach

Answer 14

90 degrees clockwise so that the left side faces anteriorly

Question 15

the dorsal mesogastrium becomes

Answer 15

the greater omentum

Question 16

the lesser omentum arises from

Answer 16

stomach rotation

Question 17

dorsal mesentery of the stomach aka

Answer 17

dorsal mesogastrium

Question 18

how does stomach rotation affect the liver

Answer 18

it moves the liver to the right side of the abdomen

Question 19

how does the retroperitoneal duodenum and pancreas occur

Answer 19

the rotation of the stomach pushes the duodenum, pancreas, and part of dorsal mesentery against the posterior body wall

Question 20

parts of dorsal mesentery of the stomach that don’t fuse with parietal peritoneum covering the posterior body wall

Answer 20

splenorenal ligament, gastrosplenic ligament, greater omentum

Question 21

ventral mesentery comes from

Answer 21

septum transversum

Question 22

ventral mesentery becomes

Answer 22

lesser omentum and falciform ligament

Question 23

what structures come off of liver bud

Answer 23

liver bud, biliary duct system, gallbladder

Question 24

what causes pancreatic buds to fuse

Answer 24

foregut rotation

Question 25

physiological herniation

Answer 25

herniation of intestines into umbilical cord

Question 26

jejunum and upper ileum formed by

Answer 26

cranial limb of midgut loop

Question 27

lower ileum through proximal 2/3 of transverse colon formed by

Answer 27

caudal limb of midgut loop

Question 28

when does physiologic herniation occur

Answer 28

6 weeks

Question 29

when does the intestine return to abdomen

Answer 29

10 weeks

Question 30

pyloric stenosis results from

Answer 30

hypertrophy of muscularis externa of pyloris

Question 31

signs of pyloric stenosis

Answer 31

projectile, nonbilious vomiting

Question 32

symptoms of pyloric stenosis begin when

Answer 32

3-5 weeks of age

Question 33

cause of pyloric stenosis

Answer 33

multifactorial (genetic and enviornmental)

Question 34

annular pancreas results from

Answer 34

the ventral pancreatic bud having two lobes that move in opposite directions during foregut rotation

Question 35

annular pancreas causes

Answer 35

an obstructive ring around the 2nd part of the duodenum at the foregut-midgut junction

Question 36

symptoms of annular pancreas present during

Answer 36

neonatal period

Question 37

symptoms of annular pancreas

Answer 37

feeding intolerance, nonbilious vomiting, abdominal distention

Question 38

omphalocele is caused by

Answer 38

midgut loop fails to return to the abdominal cavity

Question 39

what is midgut loop covered by in omphalocele

Answer 39

amnion covered parietal peritoneum

Question 40

what is gastroschisis

Answer 40

abdominal viscera herniate through body wall directly into amniotic cavity

Question 41

usual location of gastroschisis

Answer 41

to the right of the umbilicus

Question 42

cause of gastroschisis

Answer 42

defect in lateral folding of embryo that leaves a gap or weakness in anterior abdominal wall

Question 43

what is Meckel's diverticulum

Answer 43

persistence of the proximal portion of the yolk sac

Question 44

Meckel's diverticulum is most common in

Answer 44

men

Question 45

what can be present in Meckel's diverticulum

Answer 45

ectopic gastric mucosa

Question 46

usual location of Meckel's diverticulum

Answer 46

2 feet from the ileocecal junction

Question 47

if no rotation of the midgut occurs

Answer 47

small intestine ends up on the right and large intestine ends up on the left

Question 48

clockwise rotation of the midgut results in

Answer 48

large intestine is posterior to the duodenum

Question 49

what is malrotation of midgut

Answer 49

mesentery doesn't fuse properly resulting in small intestine twisting around SMA and volvulus

Question 50

symptoms of volvulus

Answer 50

vomiting, absence of stool, abdominal distention

Question 51

duodenal atresia results from

Answer 51

failed recanalization of lumen of midgut

Question 52

symptoms of duodenal atresia

Answer 52

bilious vomiting, distended abdomen, stenosis distal to ampulla of vater

Question 53

failure of neural crest cell migration leads to

Answer 53

aganglionic megacolon

Question 54

lateral fold defects include

Answer 54

omphalocele, gastroschisis

Question 55

Meckel diverticulum aka

Answer 55

persistent vitelline duct

Question 56

in what way is the spleen unique among abdominal organs

Answer 56

it is derived from mesoderm