2.5.1 GI Development Flashcards
What are the two parts of the anal canal?
Hindgut endoderm
— pecinate line —
Anal pit ectoderm
What acts as the axis of the first primary loop of the midgut?
SMA
What are the hindgut derived GI segments?
Differental growth causes expansion of the stomach into what?
Dorsal mesentary
What are the 6 midgut derived organs?
- Distal half (3rd and 4th) of the duodenum
- Jejunum
- Ileum
- Cecum and appendix
- Ascending colon
- Proximal 2/3 of the transverse colon
What two extraembryonic structures provide additional features the the primitive gut tube?
yolk sac and allantois
What does the SMA supply blood to?
Midgut and its derivative organs
The ventral mesentary forms from the lower portion of the septum transversum. What structures will this give rise to?
Future lesser omentum and falciform ligament
What this be?
Hirschsprung Dz
What might this be?
Annular pancreas (1 in 15,000)
What are the three phases of midgut development?
- Elongation, herniation, and rotation (90)
- Return to the abdominal cavity and rotation (180)
- Fixation of the mesentaries
What this be?
Imperforate anus
Identify these two structures
Left: yolk sac
Right: allantois
What is the classical sign of duodenal atresia on x-ray?
“Double bubble sign”
Also, seen with annular pancreas
The foregut endoderm proliferates to form buds for what three organs?
liver, gall bladder, and pancreas
What does the dorsal pancreatic bud give rise to?
Future minor duodenal papilla
Identify this conditon
Pyloric stenosis
What are some early derivatives of the foregut?
esophagus, stomach, liver, gall bladder, pancreas, 1st and 2nd portions of the duodenum
Meckel’s diverticulum leads to what two symptoms?
Intussesception and pain
What this be?
Gut rotation abnormalities
How is omphalocele most commonly detected and diagnosed?
Prenatal ultrasound (or AFP/apha-fetoprotein screening)
Identify
Top: Ventral mesentary
Bottom: Dorsal mesentary
Identify these structures
What this be?
Meckel’s diverticulum
Liver and gall bladder buds grow into the lower portion of the septum tranversum helping to form what structure?
Diaphragm
What this be?
Omphalocele (2.5 in 10,000 with a 25% mortality rate)
How often do atresias and stenoses occur?
1 in 5,000 births
What grows down to seperate the hindgut from the cloaca?
The urorectal septum
What does the IMA supply blood to?
The hingut and its derivative organs
What occurs in gut rotation abnormalities?
Only the intital 90 degree rotation
or
Initial 90 degree rotation clockwise and secondary 180 degree rotation counterclockwise
The two pancreatic buds migrate together and ultimately give rise to the pancreas. What is each of the buds responsible for?
Absence of a normal opening, or failure of a structure to have a lumen
Atresia
Thought to arise when two ventral pancreatic buds form and migrate in opposite directions constricting the duodenum, or when the ventral pancreatic bud fails to fully rotate posteriorly; thus a defect in VENTRAL pancreatic bud rotation.
Annular pancreas
What does the celiac artery supply blood to?
Foregut and its derivative organs
What two conditions are thought to be associated with annular pancreas?
Pancreatitis and Down Syndrome
Failure of the midgut to return to the peritoneal cavity?
Omphalocele
Failure of body wall closure followed by gut herniation.
(The failure of the anterior body wall typically occurs to the right of the umbilicus and the herniated intestines are not covered by a thin membrane)
Gastroschisis
Again, what does the ventral mesentary ultimately develop into? (2)
Lesser omentum and falciform ligament
What does the dorsal mesogastrium utimately give rise to? (2)
Greater omentum and Gastrocolic ligament
What does the ventral pancreatic bud give rise to?
Future major duodenal papilla
What is the classical presentation of pyloric stenosis?
Male baby in his 2nd-6th week of life presenting with projectile vomiting. Also suffering from hypochloremia
What this be?
Gastroschisis
Does the stomach rotate during development?
Yes, 90 degrees. It causes a change in the postion of the mesentaries
What portion of the embryo gives rise to the intraembryonic component?
endoderm-lined yolk sac
Oh my baby. What’s going on?
Duodenal atresia
What vein is contained within the falciform ligament? It ultimately gives rise to the ligamentum teres hepatis.
Umbilical vein
