Development Of Gut (3)

Question 1

What does the midgut develop into?

Answer 1

Duodenum
Jejunum
Ileum
Caecum
Ascending colon
2/3s of transverse colon

Question 2

What week of development does the midgut undergo rapid elongation?

Answer 2

6th week

Question 3

What other viscera develops at the same time as the rapid elongation of the midgut?

Answer 3

Liver

Question 4

There is limited space in the abdominal cavity as the midgut (intestinal loop) and liver develop, how does the body compensate for the lack of space in the abdominal cavity?

Answer 4

Intestinal loop herniates through the umbilical cord

Question 5

What blood vessel acts as an axis of rotation for the intestinal loop?

Where is the small intestine and large intestine positioned in relation to the SMA before rotation?

Answer 5

Superior mesenteric artery

Small intestine above
Large intestine below

Question 6

How does the intestinal loop first rotate around the superior mesenteric artery?
What position does this put the small intestine and large intestine in?

Answer 6

90 degree anti-clockwise rotation

Small intestine on RHS and Large intestine on LHS. (L for Large + L for Left)

Question 7

After the first 90 degree anti-clockwise rotation of the intestinal loop, how does it then rotate?

What position does this leave the intestines in?

Answer 7

Does 2 more 90 degree counter clockwise rotations

Small intestine to the left of the large intestine

Question 8

What part of the large intestine moves between the 2nd and 3rd rotation of the intestinal loop?

Where does it end up?

Answer 8

Caecum descends

Moving from near the liver to its normal spot in the right iliac fossa

Question 9

When does the physiological return of the midgut herniation back to the abdominal cavity occur?

Answer 9

10th week of development

Question 10

How many 90 degree anti-clockwise rotations does the midgut (intestinal loop) do in normal development?

Answer 10

3 rotations

Question 11

What is a complication if the midgut only does 1 90 degree anti-clockwise rotation instead of 3?

Answer 11

Colon is left sided (left iliac fossa instead of right)

Question 12

What happens if the intestinal loop/midgut only does 1 90 degree rotation but in the clockwise direction?

Answer 12

Transverse colon will be posterior to the small intestine instead of the normal anterior

Question 13

What is omphalocele?

Answer 13

When midgut herniation fails to return to the abdominal cavity at the 10th week of development

Question 14

How does omphalocele present?

Answer 14

The herniated contents of the midgut are covered by peritoneum so are not exposed to amniotic fluid

Question 15

What is Gastroschisis?

Answer 15

Where the abdominal wall fails to form allowing the abdominal viscera to herniate through the defect

Question 16

How do the herniated contents differ in Omphalocele and Gastroschisis?

Answer 16

Midgut contents covered with peritoneum in Omphalocele

Midgut contents in Gastroschisis not covered by peritoneum so are exposed to the amniotic fluid

Question 17

What has the higher mortality rate and why, Omphalocele or Gastroschisis?

Answer 17

Omphalocele = higher mortality rate

Omphalocele associated with more genetic abnormalities

Question 18

What is the Vitelline duct?

Answer 18

Connection between the midgut structures and the yolk sac

Question 19

When does the Vitelline duct normally regress?

Answer 19

7th week of development

Question 20

What are 3 potential Vitelline duct abnormalities?

Answer 20

Vitelline cyst

Vitelline fistula

Meckels diverticulum

Question 21

What is a Vitelline cyst?

Answer 21

When the Vitelline duct fails to fully regress leaving a patent middle section of the duct

Question 22

What is a Vitelline fistula?

Answer 22

Where there is still a complete connection between the midgut and umbilicus (Vitelline duct hasn’t regressed at all)

Can get faecal discharge from umbilicus

Question 23

What is Meckels diverticulum?

Answer 23

A small out-pouching of the small intestine (like an appendix off the small intestine)

Most common abnormality

Question 24

What complications can occur if the recanalisation of the midgut lumen is incomplete?

Answer 24

Atresia = absence of lumen

Stenosis = narrowing of the lumen

Mainly affects the duodenum

Question 25

How are the small intestine and large intestine positioned relative to the superior mesenteric artery before rotation takes place? (look at slide 5)

Answer 25

Small intestine superior

SMA

Larger intestine inferior