GIT embryology extra

Question 1

which part of the GIT gives out pockets and what do they form

Answer 1

foregut

liver
gallbladder
pancreas

Question 2

what do the lover gallbladder and pancreas develop from specifically

Answer 2

diverticulum of the cranial half of the duodenum

Question 3

when does the hepatic diverticulum form

Answer 3

in week 3

Question 4

the hepatic diverticulum contains rapidly proliferating cells but what do they penetrate

Answer 4

septum transversum

Question 5

what forms the bile duct

Answer 5

connections between the duodenum and the hepatic diverticulum

Question 6

what are hepatocytes derived from

Answer 6

endodermal cells

Question 7

what cells derive from the mesoderm of the septum transverses

Answer 7

haematopoeitic, kpffur cells and connective tissue

Question 8

when the liver becomes too large for the septum trasnversum what happens

Answer 8

protrudes into the ventral mesentery

Question 9

once the liver protrudes into the ventral mesentery what two parts are formed

Answer 9

falciform ligament

lesser omentum

Question 10

what is the bare area of the liver

Answer 10

the cranial surface of the liver which remains in contact with the spetum transversum

Question 11

what forms the coronary ligament and the triangular ligament

Answer 11

CL - around the margins of the bare area

TL - when the CL’s end at the lateral edges of the liver at the left and the right there is the..

Question 12

when is the liver 10% of total body weight

Answer 12

week 10

Question 13

why do we need a large liver as a foetus

Answer 13

haematopoesis

Question 14

what happens to the liver at birth and why

Answer 14

shrinks to 5% of total body weight

haematopoesis switching role to the bone marrow not the liver

Question 15

what week does the gallbladder and the cystic duct form

Answer 15

3

Question 16

what week does the liver start to produce bile

Answer 16

12

Question 17

what is the term of the first bowel movement of the newborn and why is it green

Answer 17

due to the liver producing bile in the foetus

Question 18

what causes neonatal jaundice and how common is it

Answer 18

60% full term babies
immature liver does not have sufficient glucuronosyltransferase to conjugate bilirubin which cause the yellow skin and yellow eyes (sclera)

Question 19

what is the scientific term for jaundice

Answer 19

hyperbilirubinaemia

Question 20

what is common complication of neonatal jaundice

Answer 20

kernicterus

Question 21

what causes kernicterus and how is it treated

Answer 21

excess unconjugated bilirubin enters the BBB and causes brain damage
phototherapy oxidises the bili so it can be excreted (but light most effective)

Question 22

during foetal development what is happening to the septic and bile duct epithelium

Answer 22

rapid proliferation and recanalisation

Question 23

what is biliary atresia, symptoms and how common

Answer 23

failure of either hepatic or bile duct epithelia to recanalise
indistinguishable from neonatal jaundice but does not respond to phototherapy

Question 24

what causes duplication of the gall bladder

Answer 24

caused by extra endodermal out pocketing during week 5/6

Question 25

how does the pancreas initially form

Answer 25

2 endodermal buds that fuse together

Question 26

when does the dorsal bud and what from

Answer 26

in week 3 from the duodenum which extends into the dorsal mesentery

Question 27

where does the ventral bud of the pancreas form

Answer 27

smaller diverticulum caudal to the developing gall badder

Question 28

what rotates as the stomach rotates which carries the ventral bud dorsally along with the bile duct

Answer 28

ventral bud

Question 29

when does fusion of the pancreas occur

Answer 29

week 6

Question 30

what parts of the pancreas do the dorsal bud and the ventral bud form

Answer 30

DB - head, body and tail of pancreas

VB - uncinate process

Question 31

what forms the main pancreatic duct

Answer 31

distal protein of the dorsal pancreatic duct and all of the ventral pancreatic duct

Question 32

what forms the accessory pancreatic duct

Answer 32

proximal portion of dorsal pancreatic duct

Question 33

where does the main pancreatic duct enter the duodenum

Answer 33

major duodenal papilla - ampulla of vater

Question 34

where does the accessory pancreatic duct enter the duodenum if it is not obliterated at birth

Answer 34

minor duodenal papilla

Question 35

how is an annular pancreas formed

Answer 35

ventral pancreatic bud can be bi lobed where the lobes migrate in opposite direction - this can compress the duodenum causing GIT obstruction

Question 36

what causes ectopic pancreatic tissue and where is it most frequently seen

Answer 36

inappropriate differentiation of endodermal cells into pancreatic tissue
most freq in duodenum or stomach mucosa

Question 37

what is the spleen derived from

Answer 37

mesoderm

Question 38

when does the spleen appear

Answer 38

week 5

Question 39

what forms the gastrosplenic ligament

Answer 39

the dorsal mesentery between the stomach and the spleen

Question 40

what forms the lienorenal (splenorenal) ligament

Answer 40

dorsal mesentery between the spleen and the kidney

Question 41

10% of the population have what associated with an abnormal spleen

Answer 41

additional mesenchymal condensations which from accessory spleen - important in medical imaging - usually found near hilum of primary spleen