Time frame for development of the GI tract
4th to 10th weeks
Txn factor for the esophagus
For the duodenum and pancreas
For the SI
For the LI
SOX2
PDX1
CDXC
CDXA
The development of the GI tract requires the communication between what two embryonic layers?
Endoderm (epithelium) and splanchnic mesoderm (mesenchyme)
How might epithelium cause an atresia in the gut tube?
Temporarily occludes it, but then never re-canalizes
Where is the oblique muscle layer when it is included in the GI wall?
Innermost, just after the submucosa
The mesentery is made from what layer?
Parietal peritoneum (splanchnic mesoderm)
Where is the only place where ventral mesentery can be seen in an adult?
Falciform ligament and lesser omentum
Innervation of the foregut
Spinal roots
Greater splanchnic n. and celiac plexus
T5-9
Innervation of the midgut
Spinal nerve roots
Lesser splanchnic n. and superior mesenteric plexus
T9-12
Innervation of the hindgut
Spinal nerve roots
Least splanchnic n. and inferior mesenteric plexus
T12-L2
In the pathway of sympathetic innervation, the “prevertebral ganglia” that the splanchnic nn. go to after leaving the abdominal sympathetic trunk are where?
Celiac, SM, and IM plexuses
Parasympathetic innervation of foregut
Midgut?
Vagus n.
SAME
Parasympathetic innervation of hindgut (w/ levels)
Pelvic splanchnic nn. (S2-4)
If urine is leaking from an umbilicus, what is the problem?
Patent allantois (to become the urachus)
If feces is leaking from an umbilicus, what is the problem?
Patent vitelline duct (to be Meckel’s diverticulum)
3 Tx’s for a double tracheoesophageal fistula
What is crucial to these?
Colon interposition
Gastric tube esophagoplasty
Gastric transposition
MUST KEEP BLOOD SUPPLY IN TACT
Esophageal diverticulum
Blind benign pouch off the side of the esophagus that could collect food/liquid
Why does the stomach turn?
Posterior grows faster than anterior, so needs more space to keep growing
If, 2-3 weeks after birth, a baby is vomiting NON-GREEN stuff after feeding, what is most likely the problem?
What can sometimes be seen externally?
Hypertrophic pyloric stenosis
Bloated stomach and/or duodenum poking through ant. abd. wall
Double bubble sign
2 bloated areas on x-ray (stomach and duodenum) due to a duodenal atresia (occlusion)
What organs develop in the ventral mesentery?
Liver and gall bladder
Stomach and part of duodenum
Why are there often 2 duodenal papillas?
B/c ventral and dorsal “buds” of pancreas were both connected until they fused
What 2 areas signal the liver to develop in the right place?
Where does it end up coming from?
Heart and septum transversum
Posterior endoderm
Why does the lesser sac become so small?
The liver grows into the right “sac” and fills it in
If someone presents w/ jaundice, dark urine, and pale stool, what is a likely Dx?
Extrahepatic biliary atresia (incomplete formation of bile duct)
Normal level of referred pain for the GB
L1
Txn factor for inducing islets of langerhaans, D-cells, and pancreatic acinar cells to form
Pax 4
Txn factor for making glucagon-producing cells
Pax 6
Cause of annular pancreas
Does not rotate w/ stomach
Most common places for accessory pancreatic tissue
Near stomach or ileum
Most common cause of gut atresias or stenoses in the duodenum
In the SI and LI?
Failure to re-canalize
Vascular compromise
Apple peel atresia
Vascular issue leads to short jejunum and small coiled ileum and LI around the SMA or its branches
At about what time is the midgut expected to “herniate” into the umbilical cord?
Why?
About when does it come back into the body?
6 weeks
Growing faster than the body has space for
10 weeks
Common problem w/ twisting of midgut after it comes out of the umbilical cord
Volvulus
When one part of the GI tract is shoved within that of another, what is that called?
Often affects what?
Intussuseption
Blood supply
Omphalocele
Unresolved umbilical herniation
Gastroschisis
Maybe linked to what behavior by mom?
Body wall doesn’t fuse, abdomen is protruding through a “hole” in the body wall w/o being in the cord
Cocaine use
Prune Belly / Eagle-Barrett syndrome
Involved w/ what layer?
Often what other abnormality?
Lack of abdominal wall muscles, abdomen is very large and unrestrained in size
Mesoderm
Cryptorchidism
Ileal fistula
Fecal matter discharges through patent vitelline duct
Hirschprung’s Disease
Megacolon
Lack of migration of neural crest cells to the hindgut, so no enteric NS for peristalsis
Name when anus does not reach the external environment
Imperforate anus
High anorectal malformation
Low
No musculature for defecation (anorectal agenesis)
Blind sac below pelvic diaphragm (anal agenesis)