Embryology Flashcards
What part of the GI tract originates from the endoderm?
Epithelium of mucosa
Associated ducts and glands
What part of the GI tract originates from the visceral mesoderm?
Lamina propria, muscularis mucosa and muscularis externa
Spleen
What part of the GI tract originates from the neural crest?
The enteric nervous system
Meissner’s plexus by week 8
How does the oesophagus form and develop?
Begins to form as the respiratory diverticulum appears in week 3
Grows alongside the heart and lungs
How does the stomach form and develop?
Starts as a fusiform dilatation
Dorsal wall grows rapidly - forms the greater curvature
Ventral wall grows slower - forms the lesser curvature
How do the dorsal and ventral mesenteries form and develop?
The begin to form and attach the gut tube to the anterior and posterior walls of the abdomen
How does the greater omentum form and develop?
Extends from the greater curvature of the stomach as the dorsal mesentery forms continues to develop into the greater omentum
How do the duodenum and pancreas form and develop into retroperitoneal organs?
The dorsal mesentery fuses with the peritoneum
How does the midgut form and develop?
It rapidly expands, forming the primary intestinal loop
As lengthening continues, it rotates 90 degrees
Cranial limb - distal duodenum, jejunum and upper ileum
Caudal limb - lower ileum, caecum, ascending colon and 2/3 of the transverse colon
How does the liver and biliary system form and develop?
The hepatic diverticulum forms
Cranial position - liver
Caudal position - bile duct
What is Meckel’s diverticulum?
Incomplete obliteration of the vitilline duct
Leaves the child with a “pouch” - diverticulum
What is a vitilline cyst?
A cyst of the vitilline duct that hasn’t been completely obliterated
What is a vitilline fistula?
The vitilline duct remains patent, forming a direct connection between the umbilicus and the ileum
What is omphalocele?
Failure of the intestines to return back into the abdomen
Presents as a shiny sac
What is gastroschisis?
Protrusion of abdominal content through the abdominal wall due to abnormal closure around the connecting stalk
