GI Embryology Flashcards
What is peritoneal reflection?
Change in direction
What classifies a structure as retro peritoneal?
Never in the peritoneal cavity and no mesentery
E.g aorta, kidneys , vena cava
What classifies as structure as secondary retro peritoneal?
Begin development in the peritoneum had a mesentery but with growth this is lost through fusion at posterior abdominal wall.
E.g asc and desc colon and duodenum.
What is fusion fascia?
Peritoneum of posterior abdominal wall is squished together with the duodenum and mesentery growing over it. It is Avascular
When Does the respiratory diverticulum develop and from what?
4th week
Grows off the ventral wall of the foregut
What divides the respiratory primordium ventrally and the oesophagus dorsally?
Tracheoesophageal septum
What foregut structures are formed in the ventral mesentery?
Liver, biliary system and part of the pancreas
What FG structures are formed in the dorsal mesentery?
Rest of pancreas
What does the liver develop from?
The hepatic bud
What happens to the duodenum in weeks 5 and 6?
Lumen is obliterated due to lining growing so quickly
What lines the primitive gut tube?
Endoderm
What are the 3 sections of the primitive gut tube?
Foregut, midgut and hind gut
What week of development does the primitive gut tube begin in?
3rd
Where does the primitive gut tube run from and to?
Starts at the stomatodeum runs rostrally to the proctodeum caudally with an opening at the umbilicus
What is the opening of the primitive gut tube to the yolk sac called?
The vitelline duct
What are the two types of mesoderm surrounding the gut called and what do they become?
Somatic mesoderm - becomes muscles and fascia of the abdominal wall.
Splanchic mesoderm develops into smooth muscle of the gut wall
What is the space created by the split in mesoderm called?
Coelomic cavity (forerunner of the pleural cavity and peritoneal cavity)
What is the point where the two sides of the abdominal wall meet in lateral folding?
Linea alba
What are the 3 layers of muscle found In The anterolateral abdominal wall?
External oblique, internal oblique and transverse abdominis
What is the inguinal canal?
An oblique passageway through the layers of abdominal wall allowing the passage of the developing testis into the scrotum
What is an umbilical hernia?
A congenital abnormality where the intestines protrude through the abdominal wall via the umbilicus
What divides the intraembryonic coelom to become what?
The diaphragm divides it into the abdominal and the thoracic cavity
What is the peritoneum?
The serous membrane that forms the lining of the abdominal cavity
What attaches the entire developing gut to the roof of the abdominal cavity?
The dorsal mesentery
What holds the foregut only to the floor of the abdominal cavity?
Ventral Mesentery
What is a mesentery?
A fold in the mesoderm allowing passage to vessels and nerves in adults
What are the adult derivatives of the foregut?
Oesophagus, stomach, pancreas, liver, gall bladder and duodenum (proximal to the bile duct)
What are the adult derivatives of the mid gut?
Duodenum (distal to bile duct) , jejunum, ileum, cecum, ascending colon and proximal 2/3 of the transverse colon
What are the adult derivatives of the hind gut?
Distal 3rd of the transverse colon, descending colon, sigmoid , rectum , upper anal canal, internal lining of bladder and urethra
What defines a Retroperitoneal structures?
Organs/structures that were never in the peritoneal cavity and never had a mesentery e,g aorta, kidneys, vena cava
