Embryology of GI tract

Question 1

What is the Liver bud an outgrowth from?
When does it appear?

Answer 1

Distal foregut
Appears in week 3

Question 2

What is the septum transversum

Answer 2

Transverse partition between pericardial cavity and abdominal cavity

Question 3

What happens to the connection between the liver bud and duodenum?

Answer 3

Narrows to bile duct

Question 4

After 36 days what outgrows from the bile duct?

Answer 4

Gall bladder

Question 5

What does mesoderm of the transversum septum form as the liver grows?

Answer 5

Greater omentum and falciform ligament

Question 6

What are the two Ventral mesentries?

Answer 6

Lesser omentum- connects liver to stomach and duodenum
Falciform ligament- connects liver to anterior abdominal wall

Question 7

When does the Stomach start to develop?

Answer 7

Week 4

Question 8

What are the 5 Stages of the development of the Midgut?

Answer 8

Elongation
Physiological Herniation
Rotation
Retraction
Fixation

Question 9

When does Physiological herniation occur? What happens?

Answer 9

Week 6
Protrusion into the umbilical cord

Question 10

What happens during Elongation in the development of the Midgut?

Answer 10

Formation of the primary intestinal loop
Connection to yolk sak (Viletine duct) narrows

Question 11

What three structures is the Cephalic limb of the Primary Intestinal loop made up from?

Answer 11

Distal part of Duodenum
Jejunum
Part of Ileum

Question 12

What 5 structures make up the Caudal limb of the Primary Intestinal loop?

Answer 12

Distal part of Ileum
Caecum
Appendix
Ascending Colon
Proximal 2/3 of transverse colon

Question 13

What does Herniate mean? What does the Intestinal loop herniate into? During which week?

Answer 13

Herniate- moves into
Umbilical Cord
6th week

Question 14

Why does the Intestinal loop herniate into the umbilical cord?

Answer 14

Abdominal cavity too small for gut and liver

Question 15

What Rotates during Stage 3 of the Development of the Midgut?

Answer 15

The caudal limb

Question 16

What direction and how many degrees does the Caudal limb rotate?

Answer 16

Anticlockwise and 90 degrees

Question 17

What do the Parts destined to be the small intestine develop during continued Elongation that the parts destined to be the large intestine do not?

Answer 17

Coils

Question 18

What Week does the gut loop return to the abdomen?

Answer 18

Week 10

Question 19

What does the gut do once it has re entered the abdominal cavity?

Answer 19

Rotates a further 180 degrees anticlockwise

Question 20

What returns to the abdominal cavity first after retraction? What returns to the abdominal cavity second? Where does each structure settle?

Answer 20

Jejenum returns first
Ileum returns second
Jejenum settles towards left and Ileum settles towards right

Question 21

What returns to the gut last during retraction? Where does it return to and where does it settle?

Answer 21

Caecum returns last to right upper quadrant
Descends and settles in Right iliac fossa

Question 22

What happens during The fixation stage? What is the layer called that forms?

Answer 22

Parietal peritoneum on the posterior body wall and the visceral peritoneum on the organ join together forming a fascial layer called toldt fascia

Question 23

What develops from the caecal bud as it descends from the upper right quadrant to the right iliac fossa?

Answer 23

Appendix

Question 24

What three processes can congenital anomalies occur with?

Answer 24

Gut rotation
Return of gut loops to abdomen
Mesentries

Question 25

What is Meckel’s diverticulum?

Answer 25

When the Vitelline duct forms an out-pouching from ileum (Congenital anomaly)

Question 26

What is the condition called when the midgut loop doesn’t return to the abdomen?

Answer 26

Omphalocele
Gut is covered with amnion

Question 27

What does the last part of the hindgut communicate with?

Answer 27

The cloaca

Question 28

What is the Cloaca?

Answer 28

Cavity of the urogenital and anorectal in early embryos

Question 29

What forms in the cloaca that separates the urogenital sinus from the cloaca?

Answer 29

Urorectal septum

Question 30

How does the Lower anal pit form?

Answer 30

Invagination of the Ectoderm

Question 31

What membrane ruptures allowing what two structures to become continuous with one and other?

Answer 31

Cloacal membrane ruptures
Allows upper and lower parts of anal canal to become continuous