Embryology

Question 1

What happens in week 1?

Answer 1

Fertilisation to implantation

Question 2

What happens in week 2?

Answer 2

Bilaminar germ disc formation
- Epiblast
- Hypoblast
Establishment of body axis

Question 3

What happens in week 3?

Answer 3

Trilaminar disc formation (gastrulation)
- Ectoderm
- Mesoderm
- Endoderm

Question 4

When is the gut tube formed?

Answer 4

Weeks 3 and 4

Question 5

What does the lateral plate mesoderm form?

Answer 5

Parietal mesoderm
Visceral mesoderm

Question 6

What closes the gut tube at its cranial end?

Answer 6

Oropharyngeal membrane

Question 7

What closes the gut tube at its caudal end?

Answer 7

Cloacal membrane

Question 8

What are the foregut structures?

Answer 8

Oeosphagus
Stomach
Mesogastrium
Duodenum
Liver
Biliary apparatus
Spleen
Pancreas

Question 9

What is the mesogastrium?

Answer 9

Mesentery of the stomach
- Greater omentum
- Lesser omentum

Question 10

What is the duodenum formed from?

Answer 10

Caudal part of foregut
Cranial part of midgut

Question 11

What is the origin of the spleen?

Answer 11

Mesoderm

Question 12

What is the origin f the pancreas?

Answer 12

Endoderm

Question 13

What are the midgut structures?

Answer 13

Duodenum
Jejunum
Ileum
Caecum
Ascending colon
2/3rds of transverse colon

Question 14

How is the primary intestinal loop formed?

Answer 14

Anticlockwise rotation
Physiological herniation of intestinal loop (Week 6)
Vitelline duct connects the ilium with yolk sac (Week 12-14)
Intestinal loop begins to move back into abdominal cavity (Week 10)

Question 15

What are the hindgut structures?

Answer 15

Distal 1/3 transverse colon
Descending colon
Sigmoid colon
Rectum
Cranial part of anal canal

Question 16

What is the end of the hindgut?

Answer 16

Cloacal membrane
Ruptures at week 7 establishing the anal canal

Question 17

What is the origin of the caudal part of the anal canal and the anal orifice?

Answer 17

Ectoderm