Development of the GIT

Question 1

What is responsible for holding the organs of the GIT in place?

Answer 1

Mesentery

Question 2

The GIT has intrinsic neurones for motility reflexes. What are intrinsic neurones?

Answer 2

A type of afferent neurone which connects motor neurones to sensory neurones

Question 3

The GIT has vagal and pelvic nerves. What do the vagal nerves do?

Answer 3

A vagus nerve is responsible for carrying signals between the heart, brain and digestive systems

Question 4

What is the parietal peritoneum?

Answer 4

The lining of the walls of the abdominal cavity

Question 5

What is the name of the membrane that surrounds the individual organs?

Answer 5

Visceral peritoneum

Question 6

Which of the 3 germ layers is the GIT formed from?

Answer 6

Endoderm

Question 7

How is the gut tube formed?

Answer 7

1) Endoderm folds and elevates
2) Endoderm folds around ventrally
3) Endoderm fuses ventrally

Question 8

Where does the splanchic mesoderm come from?

Answer 8

The lateral plate mesoderm

Question 9

What is the name of the membrane at the two openings of the primitive gut?

Answer 9

Buccopharyngeal membrane (mouth end)
Cloacal membrane (anal end)

Question 10

What does the foregut form?

Answer 10

Foregut forms the oesophagus, the stomach, the gall bladder, the bile ducts, the pancreas and the proximal duodenum

Question 11

How is the stomach formed during the rotation of the foregut?

Answer 11

1) Foregut rotates 90 degrees along the longitudinal axis
2) Tube bulges out to the left side
3) Further rotation along the ventrodorsal axis

Question 12

What is the greater omentum formed from?

Answer 12

Dorsal mesentry

Question 12

What is the lesser omentum formed from?

Answer 12

Ventral mesentry

Question 13

What do each of these ligaments in the greater omentum link together?
1) Gastrophrenic
2) Gastrocolic
3) Gastrosplenic
4) Phrenicosplenic

Answer 13

1) Stomach to diaphragm
2) Stomach to transverse colon
3) Stomach to spleen
4) Diaphragm to spleen

Question 14

What do each of these ligaments in the lesser omentum attach?
1) Hepatophrenic
2) Hepatogastric
3) Hepatooesophageal
4) Falciform

Answer 14

1) Liver to diaphragm
2) Liver to stomach
3) Liver to oesophagus
4) Liver to ventral abdominal wall

Question 15

As the stomach forms, there is also an out pocketing on the ventral side of the gut tube. What does this form?

Answer 15

• Ventral pancreatic bud and duct
• Gall bladder
• Liver buds

Question 16

The ventral pancreatic bud and duct must then move to sit alongside the dorsal pancreatic bud and duct. How does this happen?

Answer 16

1) There is a clockwise rotation through the proximal duodenum
2) Ventral and dorsal pancreatic ducts fuse

Question 17

How does the spleen form?

Answer 17

It forms from mesodermal cells in the dorsal mesentry

Question 18

What is physiological herniation?

Answer 18

The process in which the midgut grows and loops out of the umbilical cord

Question 19

What happens during physiological herniation?

Answer 19

1) Midgut lengthens out of the umbilical cord, rotates 90 degrees clockwise around the central artery within the cord
2) Intestines retract and undergo 180 degree rotation about the ventro-dorsal axis.

Question 20

What is the difference in the ascending colon between a pig, a horse, and a ruminants

Answer 20

Pigs = have a spinal loop in a 3D cone shape
Horse = don’t have a spinal loop, instead just a single large loop
Ruminants = Spinal loop in a flat plane

Question 21

What is the cloaca?

Answer 21

The common end for the hindgut and urogenital tract

Question 22

How does the hind gut form (to separate the urogenital tract and the hindgut)?

Answer 22

• Urorectal septum grows towards the cloacal membrane
• The perineal body then separates the urogenital and anal membranes