Embyology of the foregut Flashcards
What is the embryological origin of the GIT epithelium/glands/parenchyma?
endoderm
What is the embryological origin of the lamina propria, muscles, connective tissue, & other wall components in the GIT?
Splanchnic mesoderm
What closes each end of the gut tube before week 4 of development?
Oropharyngeal membrane and Cloacal membrane
What are the openings of the GIT called?
Top: Stomodeum;
Bottom: Proctodeum
What is the blood supply to the foregut?
Celiac artery
What is the sympathetic innervation of the foregut?
Celiac ganglia: T5-T9
What is the parasympathetic innervation of the foregut?
Vagus nerve
What divides the trachea and esophagus?
esophagotracheal/tracheoesophageal septum
What is polyhydramnios?
Too much fluid in the amniotic sac.
May result from tracheoesophageal malformations.
Describe the development of the stomach
- Fusiform enlargement of caudal portion
- Dorsal border is faster growing and forms the greater curvature
- Ventral border becomes lesser curvature
- Stomach rotates 90o (ventral moves right; dorsal moves left)
What is the dorsal mesentery?
- attaches stomach to posterior wall
- called the dorsal mesogastrium
- derived from mesoderm
What is the ventral mesentery?
- attaches stomach to anterior body wall
- called ventral mesogastrium
- derived from mesoderm and septum transversum
With respect to mesentery layers, where does the liver develop and what are the mesentery layers that surround it?
- Liver develops between layers of ventral mesogastrium
- Divides this layer into falciform ligament (liver to body wall) and lesser omentum (GIT to liver)
What is the free margin of the lesser omentum?
What happens to it after birth?
- Hepatoduodenal ligament portion of the lesser omentum.
- connects liver to the duodenum.
- contains bile duct, hepatic artery, and portal vein
What is the omental bursa?
- Lesser peritoneal sac
- the space behind the stomach created during rotation of the stomach
What connects the lesser peritoneal sac to the rest of the peritoneal cavity?
Epiploic foramen of Winslow
What is congenital hypertrophic pyloric stenosis?
- Thickening of the pylorus
- hypertrophy of the muscular layers of the pylorus
- -> may get polyhydramnios
- -> may get projectile vomiting
Is the duodenum intra-abdominal or retroperitoneal?
Yes, Secondary retroperitoneal
Describe the development of the duodenum
- Grows rapidly to form a C-shaped loop.
- Epithelial cells proliferate and obliterate the lumen of the duodenum.
- Recanalization (cell death) re-opens the lumen.
What is duodenal stenosis?
Partial occlusion of duodenal lumen
What is duodenal atresia?
Complete occlusion of the duodenal lumen
- -> distention of epigastic region in infants –>vomiting
- -> polyhydramnios due to lack of intestinal fluid absorption
What is a hepatic diverticulum?
“liver bud” ie. gives rise to upper (liver) and lower (gallbladder & biliary tree) divisions
- vental outgrowth from the caudal part of the foregut
Kupfer cells and hematopoietic tissue of the liver are derived from what?
mesenchyme in the septum transversum
What is the blood supply of the liver?
hepatic artery (branch of celiac artery)
What do the cystic duct and common bile duct develop from?
stalk of the liver bud (hepatic diverticulum)
What is the portal triad?
Hepatic portal vein, hepatic artery, common bile ducts.
Where is the portal triad?
Hepatoduodenal ligament (from ventral mesentery)
What makes up the ventral mesentery?
- lesser omentum
- falciform ligament
- round ligament of liver (umbilical vein)
What makes up the lesser omentum?
- hepatoduodenal ligament
- hepatogastric ligament
What is extrahepatic biliary atresia
- Failure of recanalization
- -> duplication of gallbladder
What is the sphincter of Oddi?
Sphincter in major duodenal papilla
What forms the main pancreatic duct?
Distal part of dorsal pancreatic duct & duct of ventral pancreas
What forms the accessory pancreatic duct?
Proximal part of dorsal pancreatic duct
Most of the pancreas is derived from what?
Dorsal pancreatic bud (from caudal portion of the foregut)
Name a couple pancreatic malformations
Annular pancreas (fails to correct rotation) Accessory pancreatic tissue in other structures (stomach, duodenum, or ileal diverticulum)
What is the spleen derived from?
Mass of mesenchymal cells in dorsal mesogastrium
What is the sympathetic innervation of the spleen?
T5-T9
What is the parasympathetic innervation of the spleen?
Vagus nerve
