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

Establish the body of axes

Question 3

What’s the transcription factor for establishing left sidedness?

Answer 3

PTX2

Question 4

What happens in week 3?

Answer 4

Trilaminar disc (gastrulation)

Question 5

What happens in weeks 3-8?

Answer 5

Organogenesis

Question 6

What’re the phases of embryonic development?

Answer 6

1) growth/ proliferation
2) morphogenesis
- development of shape, size of an organ or body part
3) differentiation
- maturation of physiological processes

Question 7

During what weeks may exposure to teratogens lead to major congenital abnormalities?

Answer 7

4-8

Question 8

What does the gut tube form from?

Answer 8

Endoderm lining the yolk sac during weeks 3-4

Question 9

Lateral plate mesoderm gives rise to?

Answer 9

Parietal and visceral mesoderm

Question 10

What is the gut tube closed at either end by?

Answer 10

Cranial=oropharyngeal membrane

Caudal=cloacal membrane

Question 11

Where does the laryngo-tracheal diverticulum (lung bud) develop from?

Answer 11

Ventral wall

Question 12

What divides the trachea and oesophagus?

Answer 12

Tracheo-oesophageal septum

Question 13

What rotations does the stomach undergo?

Answer 13

1) 90 degree

2) anterio-posterior to create final adult position

Question 14

What attaches the stomach to both the dorsal and ventral wall?

Answer 14

Mesogastrium

Question 15

How is the lesser sac created?

Answer 15

Rotation along longitudinal axis pulls dorsal mesentry to the left and the ventral mesogastrium is pilles to the right

Question 16

At which week does the liver bud appear at?

Answer 16

Middle of the third week

Question 17

What does the liver bud form from?

Answer 17

Outgrowth of the endoderm in the distal end of the foregut

Question 18

What does the liver bud grow into?

Answer 18

Septum transversum

Question 19

What narrows to form the bile duct?

Answer 19

Connection between the foregut and liver bud

Question 20

Ventral outgrowth from the bile duct forms what?

Answer 20

Gallbladder and cystic duct

Question 21

At which week does the spleen form?

Answer 21

5th

Question 22

The spleen is a derivative of what?

Answer 22

Mesochymal derivative

Question 23

What is the function of spleen up to week 14?

Answer 23

Acts as a haemopoeitic organ forming RBCs, WBCs and bone marrow

Question 24

Spleen function weeks 15-17?

Answer 24

Colonised by lymphocytes

Question 25

What happens to the spleen at week 23?

Answer 25

B cell precursors arrive

Question 26

What is the pancreas formed from?

Answer 26

Dorsal and ventral buds, which grow from the endodermal lining in week 5

Question 27

What is an oesophageal atresia and tracheo-oesophageal fistula?

Answer 27

If the tracheo-oesophageal septum fails to deviate correctly then there is an incomplete separation

Question 28

What’s an annular pancreas?

Answer 28

Ventral dud fails to move round the duodenum correctly. May cause duodenal stenosis Pancreatic tissue many form in other areas of the foregut= accessory pancreatic tissue

Question 29

What will the cephalon part of the primary intestinal tube form?

Answer 29

Distal duodenum Jejunum Proximal ileum

Question 30

Caudal part of primary intestinal tube will form?

Answer 30

Distal ileum Caecum Ascending Colom Proximal 2/3rds of transverse colon

Question 31

Why and when does the gut tube herniate into the extra-embryonic cavity?

Answer 31

Week 6. Allows growth. Will go back in about week 10

Question 32

What’s omphalocele?

Answer 32

Herniation of abdominal viscera through an enlarged umbilical ring

Question 33

What’s gastrochisis?

Answer 33

Herniation of contents into the amniotic cavity | Not covered by an anion or peritoneum

Question 34

What’s the endoderm/ectoderm boundary in the hindgut?

Answer 34

Cloacal membrane

Question 35

Foregut/midgut/hindgut boundaries

Answer 35

Foregut=pharynx>bile duct opening Midgut=bile duct opening>2/3 of transverse colon Hindgut=2/3 of transverse colon>rectum

Question 36

What’s the allantois?

Answer 36

Urethra and bladder

Question 37

Where does the epithelium have it’s origins?

Answer 37

Endoderm

Question 38

Connective tissue orgins?

Answer 38

Mesoderm

Question 39

Remenant of yolk sac?

Answer 39

Viteline

Question 40

What was the job of the falciforme ligament?

Answer 40

Carry O2 blood from mother to liver