Embryology of the GI System

Question 1

Molecular development of gut tube

Answer 1

initiated by transcription factors expressed in different regions of the tube

Question 2

Development of Esophagus

Answer 2

laryngetotracheal diverticulum of foregut into the surrounding splanchnic mesoderm

Question 3

Development of Stomach

Answer 3

dilation of foregut
Dorsal surface grows faster
Left moves anterior after 90 degree rotation

Question 4

Development of Liver

Answer 4

in ventral mesentery
development is blocked everywhere
cardiac region inhibits the blocking which allows liver development

Question 5

Development of Gallbladder and bile duct

Answer 5

in ventral mesentery
hepatic cords coalesce around exraembryonic veins to make sinusoids
bile duct forms
gallbladder and cystic duct are outgrowths of bile duct

Question 6

Development of Pancreas

Answer 6

both ventral and dorsal mesentery
PDX 1 - pancrease and duodenum
PDX 4 - endocrine function

Question 7

esophageal stenosis or atresia

Answer 7

narrowed or occluded esophagus

Question 8

hypertrophic pyloric stenosis

Answer 8

overgrowth
not immediately after birth
projectile vomiting of non bile

Question 9

duodenal atresia and stenosis

Answer 9

upper - no recanalization

lower - vascular compromise

Question 10

extrahepatic biliary atresia

Answer 10

bile ducts dont completely open
jaundice
dark urine
pale stool

Question 11

annular pancreas

Answer 11

anterior and posterior pancreas form ring around duodenum

presents as duodenal obstruction

Question 12

accessory or ectopic pancreatic tissue

Answer 12

most common in stomach or ileum

Question 13

apple peep atresia

Answer 13

occurs at proximal jejunum

short intestine due to proximal part being in a coil

Question 14

rotation of the foregut

Answer 14

stomach moves left
liver moves right
peritoneal cavities change size
R side gets smaller

Question 15

Rotation and fixation of midgut

Answer 15

rapid growth of midgut produces normal physiologic herniation
gut loops out into the umbilical cord and rotates 90 degrees
after 10 weeks loop returns to abdominal cavity and rotates another 180 degrees

Question 16

malroation

Answer 16

abnormally positioned visera

risk for entrapment

Question 17

volvulus

Answer 17

abnormal twisting of intestine causing obstruction

Question 18

intussusception

Answer 18

enfolding of one segment of intestine within another

Question 19

omaphalocele

Answer 19

gut herniation and covered by membranous sac

midgut fails to return to abdominal cavity

Question 20

gasroschisis

Answer 20

anterior abdominal wall musculature to close during folding
gut herniation not covered by membranous sac
more frequent in younger women who use cocaine

Question 21

prune belly syndrome

Answer 21

anterior abdominal wall musculature is deficient or absent 
urinary tract anomalies 
bilateral cryptorchidism 
most common in males 
failed mesoderm development

Question 22

ileal diverticulum

Answer 22

meckel’s diverticulum

failure of the vitelline duct to close

Question 23

enteric neurons plexi

Answer 23

myenteric plexus - develops 1st and occupies a postion b/w longitudinal and circular mm layers
submucosal plexus - forms later in gestation and resides w/in submuucosa

Question 24

hirschsprung’s disease

Answer 24

both enteric plexus are affected
myenteric is more effected
no movement of mm so bowel is obstructed