2.5.1 GI Development

Question 1

What are the two parts of the anal canal?

Answer 1

Hindgut endoderm

— pecinate line —

Anal pit ectoderm

Question 2

What acts as the axis of the first primary loop of the midgut?

Answer 2

SMA

Question 3

What are the hindgut derived GI segments?

Answer 3

Question 4

Differental growth causes expansion of the stomach into what?

Answer 4

Dorsal mesentary

Question 5

What are the 6 midgut derived organs?

Answer 5

1. Distal half (3rd and 4th) of the duodenum
2. Jejunum
3. Ileum
4. Cecum and appendix
5. Ascending colon
6. Proximal 2/3 of the transverse colon

Question 6

What two extraembryonic structures provide additional features the the primitive gut tube?

Answer 6

yolk sac and allantois

Question 7

What does the SMA supply blood to?

Answer 7

Midgut and its derivative organs

Question 8

The ventral mesentary forms from the lower portion of the septum transversum. What structures will this give rise to?

Answer 8

Future lesser omentum and falciform ligament

Question 9

What this be?

Answer 9

Hirschsprung Dz

Question 10

What might this be?

Answer 10

Annular pancreas (1 in 15,000)

Question 11

What are the three phases of midgut development?

Answer 11

1. Elongation, herniation, and rotation (90)
2. Return to the abdominal cavity and rotation (180)
3. Fixation of the mesentaries

Question 12

What this be?

Answer 12

Imperforate anus

Question 13

Identify these two structures

Answer 13

Left: yolk sac

Right: allantois

Question 14

What is the classical sign of duodenal atresia on x-ray?

Answer 14

“Double bubble sign”

Also, seen with annular pancreas

Question 15

The foregut endoderm proliferates to form buds for what three organs?

Answer 15

liver, gall bladder, and pancreas

Question 16

What does the dorsal pancreatic bud give rise to?

Answer 16

Future minor duodenal papilla

Question 17

Identify this conditon

Answer 17

Pyloric stenosis

Question 18

What are some early derivatives of the foregut?

Answer 18

esophagus, stomach, liver, gall bladder, pancreas, 1st and 2nd portions of the duodenum

Question 19

Meckel’s diverticulum leads to what two symptoms?

Answer 19

Intussesception and pain

Question 20

What this be?

Answer 20

Gut rotation abnormalities

Question 21

How is omphalocele most commonly detected and diagnosed?

Answer 21

Prenatal ultrasound (or AFP/apha-fetoprotein screening)

Question 22

Identify

Answer 22

Top: Ventral mesentary

Bottom: Dorsal mesentary

Question 23

Identify these structures

Answer 23

Question 24

What this be?

Answer 24

Meckel’s diverticulum

Question 25

Liver and gall bladder buds grow into the lower portion of the septum tranversum helping to form what structure?

Answer 25

Diaphragm

Question 26

What this be?

Answer 26

Omphalocele (2.5 in 10,000 with a 25% mortality rate)

Question 27

How often do atresias and stenoses occur?

Answer 27

1 in 5,000 births

Question 28

What grows down to seperate the hindgut from the cloaca?

Answer 28

The urorectal septum

Question 29

What does the IMA supply blood to?

Answer 29

The hingut and its derivative organs

Question 30

What occurs in gut rotation abnormalities?

Answer 30

Only the intital 90 degree rotation or Initial 90 degree rotation clockwise and secondary 180 degree rotation counterclockwise

Question 31

The two pancreatic buds migrate together and ultimately give rise to the pancreas. What is each of the buds responsible for?

Answer 31

Question 32

Absence of a normal opening, or failure of a structure to have a lumen

Answer 32

Atresia

Question 33

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.

Answer 33

Annular pancreas

Question 34

What does the celiac artery supply blood to?

Answer 34

Foregut and its derivative organs

Question 35

What two conditions are thought to be associated with annular pancreas?

Answer 35

Pancreatitis and Down Syndrome

Question 36

Failure of the midgut to return to the peritoneal cavity?

Answer 36

Omphalocele

Question 37

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_)

Answer 37

Gastroschisis

Question 38

Again, what does the ventral mesentary ultimately develop into? (2)

Answer 38

Lesser omentum and falciform ligament

Question 39

What does the dorsal mesogastrium utimately give rise to? (2)

Answer 39

Greater omentum and Gastrocolic ligament

Question 40

What does the ventral pancreatic bud give rise to?

Answer 40

Future major duodenal papilla

Question 41

What is the classical presentation of pyloric stenosis?

Answer 41

Male baby in his 2nd-6th week of life presenting with projectile vomiting. Also suffering from hypochloremia

Question 42

What this be?

Answer 42

Gastroschisis

Question 43

Does the stomach rotate during development?

Answer 43

Yes, 90 degrees. It causes a change in the postion of the mesentaries

Question 44

What portion of the embryo gives rise to the intraembryonic component?

Answer 44

endoderm-lined yolk sac

Question 45

Oh my baby. What's going on?

Answer 45

Duodenal atresia

Question 46

What vein is contained within the falciform ligament? It ultimately gives rise to the ligamentum teres hepatis.

Answer 46

Umbilical vein