Embryology of the GI Tract

Question 1

What happens by week 4

Answer 1

Endodermal tube running thought the centre of the emrbyo is present

Question 2

What happens to the cloaca

Answer 2

develops into both parts of the urinary system and also for the hind gut

Question 3

What are the 2 origins of the GI Tract

Answer 3

Endoderm and Visceral mesoderm

Question 4

What does the endoderm form

Answer 4

Epithelium of mucosa and associated ducts and glands

Question 5

What does the visceral mesoderm surround

Answer 5

Lamina propria
Muscularis mucosa and muscularis externa
CT of submucosa and External CT

Question 6

What is the endoderm suspended in a bit of?

Answer 6

The mesoderm

Question 7

What is the dorsal mesogastrium associated with?

Answer 7

Stomach, duodenum and mesentery proper (largest part of the dorsal mesentery associated with the small intestine

Question 8

What happens to the dorsal mesogastrium

Answer 8

Moves downwards and forwards to become the greater omentum

Question 9

How are the mesenteries brought into their final positions

Answer 9

Rotation of different parts of the gut

Question 10

When is the oesophagus distringuishable by?

Answer 10

End of week 4

Question 11

What develops in terms of the oesophagus in week 5

Answer 11

Circular muscle

Question 12

What develops in terms of the oesophagus in week 8

Answer 12

Longitudinal muscle

Question 13

What does the dilatation indicate at the end of week 4?

Answer 13

The stomach

Question 14

How is the unusual shape of the stomach brought about

Answer 14

Swelling is not growing at a uniform rate - quicker on the left border. As it grows it starts to undergo a rotation

Question 15

Where will the original left side of the stomach lie

Answer 15

Anteriorly

Question 16

Where will the original right side of the stomach lie

Answer 16

Posteriorly

Question 17

What also rotates at the same time as the stomach

Answer 17

Vagus nerves

Question 18

Where does the greater curvature move

Answer 18

Slightly inferiorly pointing down

Question 19

Where does the lesser curvature end up pointing

Answer 19

Slightly downwards

Question 20

What forms the lesser sac

Answer 20

Growth and rotations of the stomach

Question 21

What else does the growth and rotation of the stomach cause

Answer 21

The dorsal mesentery to bulge

Question 22

What forms the greater omentum

Answer 22

Continued growth of the dorsal mesentery

Question 23

What 2 things form from the ventral mesentery

Answer 23

Lesser omentum and falciform ligament

Question 24

What 3 parts make up the duodenum and what do they make up

Answer 24

Caudal portion of foregut - parts 1 and 2 of duodenum
Cranial portion of midgut - parts 3 and 4 of duodenum
Duodenal loop is directed to the right due to the rotation of the stomach

Question 25

Describe the growth of the liver bud

Answer 25

Into the mesoderm of the septum Transversum

Question 26

What is the duodenum closely associated with

Answer 26

The liver, gall bladder and pancreas

Question 27

What is important for the formation of the diaphragm

Answer 27

septum transversum

Question 28

What is the gall bladder associated with

Answer 28

The posterior aspect of the liver

Question 29

What does the mesoderm of septum transversum give rise to

Answer 29

The development of hepatocytes and the lining of the biliary tree

Question 30

What does either side of the liver go on to be?

Answer 30

The lesser omentum

Question 31

Where do the pancreas and the common bile duct form from?

Answer 31

Proliferation of the endoderm

Question 32

What gives rise to the gall bladder

Answer 32

Diverticulum

Question 33

Name the two buds of the pancreas

Answer 33

Ventral pancreatic bud and dorsal pancreatic bud

Question 34

What supplies the dorsal pancreatic bud

Answer 34

The celiac axis

Question 35

What supplies the ventral pancreatic bud

Answer 35

Superior mesenteric artery

Question 36

HOw does the ventral pancreatic duct migrate?

Answer 36

It twists so that it lies adjacent to the dorsa pancreatic duct

Question 37

What happens as the ventral pancreatic duct migrates?

Answer 37

It pulls the common bile duct and the gall bladder closer together

Question 38

In what direction does the pancreas move?

Answer 38

Clockwise

Question 39

Where is the spleen derived from?

Answer 39

Mesoderm (not gut tube)

Question 40

When does the spleen develop

Answer 40

week 5

Question 41

What is the position of the spleen dictated by

Answer 41

The rotation of the stomach

Question 42

When does the spleen develop into a lymphatic organ?

Answer 42

Weeks 15-18

Question 43

What comprises the midgut

Answer 43

``` Second half of duodenum Jejunum Ileum Caecum and appendix Ascending colon Proximal 2/3rd of transverse colon ```

Question 44

What happens at the beginning of week 4 in the midgut

Answer 44

Communicates with the yolk sac along its length

Question 45

What happens during week 4 in the midgut

Answer 45

Connection with the yolk sac narrows

Question 46

What happens to the midgut by the end of week 4

Answer 46

Connected to the yolk sac via narrow vitelline duct

Question 47

What happens in week 5 in terms of the midgut

Answer 47

The midgut has outgrown the embryo and bulges ventrally into the umbilicus

Question 48

What occupies the majority of the abdominal space

Answer 48

The liver

Question 49

What direction does the midgut rotate as you look at it

Answer 49

Anticlockwise

Question 50

What acts as an axis for the rotation to occur around

Answer 50

Superior mesenteric artery

Question 51

What does the caecal bud develop into and when does this happen

Answer 51

Caecum and the appendix | Week 8

Question 52

When does re-entry of the midgut into the body cavity occur

Answer 52

Around week 10

Question 53

What returns first?

Answer 53

Small intestine

Question 54

Describe the movement of the caecum

Answer 54

It moves back in last and lies below the liver in the Upper right quadrant. It will then move down towards the right ileac fossa.

Question 55

What is a vitelline cyst

Answer 55

A fibrous plaque

Question 56

When does the formation of the definitive gut lumen occur?

Answer 56

Weeks 5-9

Question 57

Why does the lumen of the gut initially become ecluded

Answer 57

The endodermal lining is going to proliferate