GI Embryology Flashcards
(33 cards)
How does the embryonic folding help with development of the GI system?
Cephalocaudal fold = creates cranial and caudal pockets from yolk sac endoderm - begins gut development
Lateral fold = primitive gut becomes tubular
What is the gut tube?
Endoderm lined tube running the length of the body
Where does the gut tube have an opening?
Umbilicus
What lines the gut tube?
Splanchnic mesoderm
How is the gut divided embryonically?
Foregut = blind diverticulum - buccopharyngeal membrane
Midgut = continuous with yolk sac
Hindugt = blind diverticulum - cloacal membrane Ho
What is derived from the foregut?
Oesophagus Stomach Pancreas Liver Gall bladder Duodenum - proximal to ampulla of Vater
What is derived from the midgut?
Duodenum - distal to ampulla of Vater Jejenum Ileum Caecum Ascending colon Proximal 2/3 transverse colon
What is derived from the hindgut?
Distal 1/3 transverse colon Descending colon Sigmoid colon Rectum Upper anal canal Lining of bladder + urethra
What is the intraembryonic coelom?
Large cavity formed as embryo folds - lined with splanchnic and somatic mesoderm
Later divided by future diaphragm
How do the mesenteries form?
Primitive gut is suspended in intraembryonic coelom
Splanchnic mesoderm surrounds gut
Mesentery formed by a condensation of this mesoderm
Where does a dorsal mesentery form?
Whole gut tube
Where does a ventral mesentery form?
Foregut
How do the greater and lesser sacs form?
Dorsal + ventral mesenteries in foregut split cavity into right and left sacs
Right sac = lesser sac
Left sac = greater sac
How does the greater omentum form?
From dorsal mesentery
How does the lesser omentum form?
From ventral mesentery
How does the foregut separate from the respiratory tract?
Respiratory diverticulum forms in the ventral wall of the foregut
Seperated by tracheoesophageal septum
- Ventrally = respiratory pricordium
- Dorsally = oesophagus
What influences the position of the greater/lesser sacs?
Rotation of stomach
How does the stomach rotate?
90 degress around long axis
Anticlockwise around dorsal-ventral axis
Where does the liver develop?
In the ventral mesentery
Where does the pancreas develop?
In the ventral mesentery
- uncinate process
- inferior head
In the dorsal mesentery
- superior head
- neck
- body
- tail
What causes the shape of the duodenum?
Rotation of the stomach
Why is the duodenum secondarily peritoneal?
Rotation of the stomach pushes duodenum against posterior abdominal wall
Which structures in the foregut are secondarily retroperitoneal?
Duodenum
Pancreas
What is formed by the midgut as it elongates?
Primary intestinal loop
