gut formation

Question 1

blood supply to each region of gut

Answer 1

foregut- celiac artery

midgut- superior mesenteric artery

hindgut- inferior mesenteric artery

Question 2

how is the gut tube attached?

Answer 2

attached to the dorsal body wall by the dorsal mesentery

Question 3

what splits the dorsal mesentery?

Answer 3

liver

Question 4

what does the liver split the mesentery into?

Answer 4

lesser momentum between the stomach and liver

falciform ligament between liver and anterior abdominal wall

Question 5

what is the first region to rotate?

Answer 5

stomach

Question 6

two rotations of stomach

Answer 6

left to anterior

caudal to right

Question 7

what do the rotations of the stomach result in?

Answer 7

the movement of the dorsal mesentery forming the greater and lesser omen

Question 8

stomach differentiation

Answer 8

2nd month

appearance of rug and gastric pits

differentiation requires EMT

Question 9

Problem with stomach development

Answer 9

pyloric stenosis

Question 10

pyloric stenosis explained

Answer 10

failure to form muscular structure at pyloris

lack of SOX9

abnormality of pyloric sphincter, resulting in projective vomiting

Question 11

important signals in formation of liver

Answer 11

FGF signals from adjacenct cardiac region induce liver field

Question 12

what structure does the liver originate from?

Answer 12

the gut tube

midpoint of the descending duodenum

Question 13

stages of liver development

Answer 13

1. hepatic diverticulum moves into the ventral mesentery
2. branch into hepatic cords
3. hepatic cords communicate with septum transverse mesoderm to branch into hepatic bud that forms the liver and cystic bud that forms the gall bladder
4. liver suddenly begins to grow very rapidly in 10th week
5. bile production develops in 12th week

Question 14

gut diverticula definition

Answer 14

outpouching of gut tube

Question 15

why is the development of the pancreas unusual?

Answer 15

develops from two distinct buds

Question 16

from which part does the pancreas arise of the gut tube?

Answer 16

mid part of the duodenum

Question 17

explain two buds

Answer 17

dorsal bud- body and tail

smaller ventral bud- uncinate process and head

Question 18

what induces the buds to form?

Answer 18

fgf10 from notochord for dorsal bud

Vegf for ventral;

Question 19

where do the exocrine and endocrine cells develop from?

Answer 19

dorsal bud

Question 20

how do pancreatic buds develop?

Answer 20

branching morphogenesis

1. free ventral pancreatic bud rotates around the axis of the duodenum and joins the dorsal bud

Question 21

abnormalities of pancreatic rotation

Answer 21

annular pancreas

pancreatic tissue surrounds the duodenum and constricts it

Question 22

what occurs due to expansion of liver?

Answer 22

stomach pushed to the right

pancreas pushed posteriorly causing it to join with the dorsal body wall, becoming secondarily retroperitoneal

Question 23

what forms the axis for the midgut rotation?

Answer 23

superior mesenteric artery and vitelline duct

Question 24

what causes asymmetry of gut?

Answer 24

asymmetric expression of BMP2 in gut and mesentery drives expression and rotation

Question 25

stages of midgut rotation

Answer 25

1. proliferation in midgut causing increased growth 2. the gut tube rotates 90 degrees around the axis of the vitelline gut 3. growth becomes excessive, exceeding the capacity of the coelomic cavity 4. undergoes physiological herniation where it moves out into the umbilical cord 5. gut returns to abdominal cavity, cecum moves down 6. further 180 degree anti clockwise rotation, leading to a total of 270 degrees anticlockwise

Question 26

hindgut derivatives

Answer 26

1/3 distal transverse colon descending colon rectum superior part of anal canal

Question 27

what happens during rotation?

Answer 27

ascending and descending colon pushed against posterior wall leading to formation of retroperitoneal structures

Question 28

what do the gut tube and urogenital tube open into?

Answer 28

the cloaca

Question 29

what happens to the cloaca after?

Answer 29

urorectal septum grows down between the two of them to partition them separating the urogenital system from rectal form separate anus and urethra

Question 30

what is the enteric nervous system formed of?

Answer 30

neural crest cells migrate along the gut tube

Question 31

problem with neural crest cells

Answer 31

hirschprung's disease failure of neural crest cell migration absence of enteric nervous system

Question 32

how does the spleen develop?

Answer 32

separate to the gut entirely mesodermal

Question 33

hiatus hernia definition

Answer 33

problem with the septum transversum, weaker diaphragm, causes stomach to be lodged in mediastinum