19. Embryology 3

Question 1

When does development of the lung begin?

Answer 1

Week 3

Question 2

How does the liver begin developing?

Answer 2

The hepatic diverticulum (liver bud) starts as an out-pocket of the duodenum.
It develops very quickly and penetrates the septum transversum (future diaphragm).
Here it develops further.

Question 3

How is the bile duct formed?

Answer 3

The connection between the hepatic diverticulum and duodenum narrows to form bile duct.

Question 4

What germ layer is the liver formed from?

Answer 4

Endoderm = Hepatocytes
Mesoderm = Heamotopoietic, Kupffer cells, connective tissue

Question 5

The liver develop in the dorsal mesentery.

True or False?

Answer 5

FALSE

Ventral Mesentery

Question 6

The liver causes a mesentery to divide into 2 parts.

Identify these.

Answer 6

Ventral mesentery:

1. Falciform ligament
2. Lesser omentum

Question 7

What is the ‘bare area’ of the liver and what are its boundaries?

Answer 7

Area of liver with no peritoneum (basically stuck to diaphragm).

1. Coronary ligaments - outline area
2. L+R Triangular ligaments - Edges where coronary ligaments join

Question 8

The liver is larger shrinks at birth.

True or False?

Answer 8

TRUE

Switches function from making red blood cells to filtering blood

Question 9

The cystic duct is formed from an outgrowth of gut tube.

True or False?

Answer 9

FALSE

Outgrowth from bile duct. Gallbladder also develops from the bile duct.

Question 10

Why is a baby’s first poop dark green?

Answer 10

High bile concentration.

A load of bile that had been chilling in the gut tube during development is excreted.

Question 11

What is the cause of neonatal jaundice?

Answer 11

If the liver cannot yet conjugate bilirubin, it cannot be excreted.
Therefore, it collects in the body and causes yellow skin and sclera (whites of eyes).

Question 12

How and why is neonatal jaundice treated?

Answer 12

Kernicterus = Excess unconjugated bilirubin crosses the blood-brain barrier and cause brain damage.
Phototherapy breaks down the bilirubin so that it can be excreted.

Question 13

What is biliary atresia and how does it occur?

Answer 13

Narrowing of the biliary system tubes which prevents bile from passing into intestine.
This can occur if recanalisation of the hepatic or bile duct fails.
Similar symptoms as jaundice, but cannot be treated by phototherapy.

Question 14

How does a duplicated gall bladder arise?

Answer 14

An extra out-pocket of endoderm instead of just one.

Question 15

How does the pancreas begin developing?

Answer 15

2 endodermal buds fuse - ventral & dorsal buds around duodenum.
When the stomach rotates (90 clockwise) the ventral bud is rotates lie behind the dorsal bud & fuse.
Ventral bud forms ‘uncinated process’.
Dorsal bud forms the rest of pancreas.

Question 16

The main pancreatic duct & the accessory pancreatic duct both enter the intestine at the Ampulla of Vater.
True or False?

Answer 16

FALSE

Accessory pancreatic duct enters into intestine separately.

Question 17

What is an annular pancreas & how does it occur?

Answer 17

Obstruction of duodenum by pancreas.
If the ventral bud is bilobed (two buds), each bud can go to either side of the duodenum during rotation and compress the tube.

Question 18

What is ectopic pancreatic tissue?

Answer 18

Pancreatic cells that develop in places they shouldn’t be.

Question 19

How does the spleen begin developing?

Answer 19

Derived from mesoderm(unlike rest of abdominal organs).
Week 5 forms in dorsal mesentery.
Rotation of stomach brings it onto left hand side.

Question 20

Where is the lienorenal ligament found?

Answer 20

Lienorenal ligament = dorsal mesentery between spleen & kidney