Embryology Of GIT

Question 1

GIT development connection with aorta

Answer 1

▪️begins as one long tract
-fore-gut, mid-gut, hind-gut
▪️grows parallel to abdominal aorta with a single artery connecting to each part
▪️GIT attached to the back of the embryo by dorsal mesentery/mesogastrium- FMH-gut
▪️small anterior portion of GIT is also connected to the anterior wall by ventral mesentery- only foregut
-GIT is intraperitoneal
-aorta is reteroperitoneal
▪️gap between GIT and aorta which allows vessels to connect

Question 2

Development of foregut

Answer 2

-weeks 4-5
▪️small dilation to the left
▪️stomach has front and back attachment (dorsal and ventral mesogastrium)
▪️diverticulum from foregut
-VM- liver, gallbladder, ventral pancreatic bud
-DM-pancreas, spleen(not GI organ)
▪️liver splits VM into two
-falciform ligament- liver to anterior wall
-lesser omentum-stomach to liver

Question 3

Rotation of the foregut

Answer 3

▪️stomach rotated clockwise 90degress
-GC moves left to be anterior
-pylorus/LC moves right therefore liver goes to the right
▪️rotation traps peritoneal sac behind the stomach- lesser sac

Question 4

Development of midgut and hindgut

Answer 4

▪️midgut grows in length and bends to form a loop
-at apex it is connect to yolk sac by vitelline duct- nutrients feed directly into intestine
▪️loop forms around SMA
▪️Midgut- 2nd part of duodenum to last part of transverse colon
-upper part of bend grows in length and give rises to coils of SI (cephalic limb)
-lower part of bend grows in width to give rise to parts of LI (caudal limb)
▪️as it grows and coils, it needs more room so it herniates out abdominal cavity into umbilicus
-continues to grow in length and rotates in a controlled way 270degrees AC around SMA
▪️when there is enough room in abdominal cavity, it comes back in and keeps rotating to get to right place (week 10)