GI Embryology

Question 1

The primitive gut tube is formed from what type of folding during weeks 3-4?

Answer 1

Cranio-caudal

Question 2

Where is the epithelial lining derived from?

Answer 2

Endoderm

Question 3

Where are smooth muscle and connective tissue derived from?

Answer 3

surrounding visceral mesoderm

Question 4

Where is visceral peritoneum derived from?

Answer 4

Visceral mesoderm

Question 5

Where is parietal peritoneum derived from?

Answer 5

Parietal mesoderm

Question 6

What does the dorsal mesentery suspend from the posterior abdominal wall?

Answer 6

Primitive gut tube

Question 7

Where does the dorsal mesentery extend from?

Answer 7

Lower oesophagus to cloaca

Question 8

Where does the ventral mesentery extend from?

Answer 8

Lower oesophagus to 1st part of duodenum

Question 9

Which mesentery is the falciform ligament and lesser omentum formed from - dorsal or ventral?

Answer 9

Ventral mesentery

Question 10

What 3 things do mesenteries supply?

Answer 10

1) Blood
2) Lymph
3) Nerves

Question 11

What are arteries of the GI tract derived from?

Answer 11

Vitelline arteries

Question 12

Formation of definitive gut lumen:

What happens in week 6?

Answer 12

Proliferation of endoderm occludes gut tube

Question 13

Formation of definitive gut lumen:

What is recanalisation and when does it occur?

Answer 13

Creation of vacuoles

Week 7-8

Question 14

Formation of definitive gut lumen:

What happens in week 9?

Answer 14

Vacuoles coalesce to fully recanalise gut tube

Epithelium further differentiates

Question 15

What occurs from abnormal recanalisation?

Answer 15

Duplications of GI tract

Question 16

What occurs from incomplete recanalisation?

Answer 16

Narrowing (stenosis) or blocking (atresia) of gut tube

Question 17

What is polyhydramnios?

Answer 17

Separation of proximal and distal ends of oesophgaus to prevent foetus swallowing amniotic fluid by returning it to mother’s circulation

Question 18

What week does the oesophagus form and where does it form in relation to the lung bud?

Answer 18

Week 4

Caudually

Question 19

Which mesoderm forms smooth muscle and endodermal epithelial lining?

Answer 19

Visceral mesoderm

Question 20

Which mesoderm forms some skeletal muscle?

Answer 20

Paraxial mesoderm

Question 21

During which weeks does the oesophagus lengthen rapidly as the stomach descends to the abdomen?

Answer 21

Weeks 4-7

Question 22

How does part of the stomach position following insufficient elongation?

Answer 22

Supradiaphragmatically

Question 23

In what week does the dilation of the foregut expose the stomach?

Answer 23

Week 4

Question 24

What type of growth in the foregut takes place during week 5?

Answer 24

Differential growth

Question 25

When the stomach rotates craniocaudally what is the space created behind it called?

Answer 25

Omental bursa

Question 26

What connects the greater and lesser sacs?

Answer 26

Epiploic foramen

Question 27

What causes pyloric stenosis (narrowing of pyloric sphincter)?

Answer 27

Hypertrophy of smooth muscle

Question 28

Is congenital pyloric stenosis more common amongst males or females?

Answer 28

Males (5:1 ratio of males:females)

Question 29

Which of the following processes are restricted with pyloric stenosis: - gastric motility - gastric emptying - gastric digestion

Answer 29

Gastric emptying

Question 30

During which weeks does the stomach undergo rotation?

Answer 30

Weeks 7-8

Question 31

In which direction and by what angle does the stomach rotate?

Answer 31

90* clockwise around craniocaudal axis

Question 32

Stomach rotation: | What happens to lesser curvature?

Answer 32

Moves from ventral to right

Question 33

Stomach rotation: | What happens to greater curvature?

Answer 33

Moves from dorsal to left

Question 34

Stomach rotation: | What happens to left vagus?

Answer 34

L vagus trunk becomes ventral

Question 35

Stomach rotation: | What happens to right vagus?

Answer 35

R vagus trunk becomes dorsal

Question 36

What are the 2 origins of the duodenum?

Answer 36

Foregut | Midgut

Question 37

In which week does the duodenum elongate?

Answer 37

Week 4

Question 38

During which week does the midgut and dorsal mesentery undergo rapid elongation? What is formed as a result?

Answer 38

Week 5 | Primary intestinal loop

Question 39

What happens to the midgut during week 6?

Answer 39

Rapid elongation of midgut | Rapid liver growth

Question 40

Rotation of midgut: | In which direction and by what angle does the midgut rotate?

Answer 40

90* anticlockwise

Question 41

Rotation of midgut: | Which direction do the cranial and caudal limbs move?

Answer 41

Cranial - right | Caudal - left

Question 42

Rotation of midgut: | What happens during week 10?

Answer 42

Midgut returns to abdomen | Rotates 180* anticlockwise

Question 43

Rotation of midgut: | During week 10 the caecum develops wormlike diverticulum - what are these called?

Answer 43

Vermiform appendix

Question 44

Rotation of midgut: | During which week does the midgut completely return to the abdomen and undergoes 270* anticlockwise rotation?

Answer 44

Week 11

Question 45

What is the ileal diverticulum a remnant of?

Answer 45

Vitilline duct

Question 46

What is omphalocele?

Answer 46

Failure of midgut to return to abdomen in week 10