Embryology of the GI

Question 1

Define Gastrulation

Answer 1

When the bi-laminar disc is converted into the tri-laminar disc.

Question 2

When is the bi-laminar disc formed ?

Answer 2

week 2

Question 3

What are the layers and sacs preset in the bi-laminar layer ?

Answer 3

Epiblast and hypoblast

Amniotic sac and yolk sac

Question 4

When is the tri-laminar disc formed ?

Answer 4

week 3

Question 5

What are the layers present in the tri-laminar layer ?

Answer 5

Ectoderm, Mesoderm and Endoderm

Question 6

What week does the primordial gut tube form ?

Answer 6

week 4

Question 7

What layer of the tri-laminar disc forms the primordial gut tube ?

Answer 7

Endoderm

Question 8

At which end of the primitive gut tube is the esophagus formed ?

Answer 8

The cranial end

Question 9

On which wall of the foregut do the lung buds develop ?

Answer 9

The ventral wall of the foregut

Question 10

What is esophageal atresia ?

Answer 10

When the tracheoesophageal septum divides incorrectly causing incomplete separation of the esophagus and the trachea

Question 11

Around which week does the stomach begin to form?

Answer 11

week 4

Question 12

How is the stomach formed?

Answer 12

The foregut rotates anterior posterior 2 times to create the stomach

Question 13

How many rotations are required for the stomach to be created ?

Answer 13

2

Question 14

What do these rotations that the stomach must complete create ?

Answer 14

The greater and lesser curves

Question 15

The dorsal mesentery develops into which upper GI organ ?

Answer 15

The spleen

Question 16

The ventral mesentery develops into which upper GI organ ?

Answer 16

The liver

Question 17

Wht ca be found posterior to the stomach ?

Answer 17

The lesser sac

Question 18

What makes the C-shape of the duodenum thats seen in the adult abdomen ?

Answer 18

The rotation of the stomach also rotates the duodenum giving it its typical C-shape

Question 19

What parts of the bowel are formed from the primitive midgut tube ?

Answer 19

The duodenum

jejuno-ileum ad proximal colon

Question 20

What week does the mid gut undergo rotation ?

Answer 20

Around week 6

Question 21

What kind of rotation does the midgut undergo ?

Answer 21

90 degrees clockwise

Question 22

If the ventral bud fails to migrate around the duodenum correctly then this creates____

Answer 22

an annular pancreas

Question 23

What is physiological herniation and why does the midgut undergo this process?

Answer 23

When the mid gut herniated out into the umbillicus in order for the gut to grow in length.

Question 24

At which week does the physiological herniation stop ?

Answer 24

Around week 10 the gut tube returns to the inside of the embryo when there is more room inside the abdomen.

Question 25

What is an omphalocele ?

Answer 25

Herniation of abdominal viscera through a large umbilical ring or failure of retraction of umbilical ring. Usually covered in a layer of amnion.

Question 26

What is Gastrochisis ?

Answer 26

Where the contents of the midgut herniate right through the body wall into he amniotic cavity. The contents will not be covered by a layer of peritoneum or amnion.

Question 27

What is Meckel's Diverticulum ?

Answer 27

Remnants of a vitaline duct within the bowel

Question 28

The primitive hindgut develops into which adult structures ?

Answer 28

1/3 of the distal transverse colon, the descending colon, the sigmoid colon, the upper part of the rectum and the anal canal.

Question 29

Which primitive layer lines the bladder and the urethra ?

Answer 29

The endoderm

Question 30

``` The conditions: Urorectal fistula Rectovagial fistula Rectoanal atresia are all caused by which defect ? ```

Answer 30

In complete separation of the hindgut from the urogenital sinus by the urorectal septum