What kind of folding does the embryo undergo in the fourth week?
What is the importance of lateral folding of the embryo?
- Creates ventral body wall
- Primitive gut becomes tubular
Draw a diagram illustrating lateral folding of the embryo.
Label the tubular primitive gut
What is the importance of craniocaudal folding of the embryo?
Creates cranial and caudal pockets from the yolk sac endoderm
What is the significance of the cranial and caudal pockets of the yolk sac endoderm?
It is the beginning of primitive gut development
Draw a diagram illustrating craniocaudal folding of the embryo
What is the primitive gut tube lined with?
What regions is the primitive gut tube divisible into?
What is the importance of the divisions of the primitive gut tube?
They remain fundamental to the anatomy of the adult GI tract, and determine its nerve and blood supply
When does the development of the primitve gut tube begin?
In the 3rd week
What is the first step in the development of the primitive fut tube?
It 'pinches off' from the yolk sac cavity
Where does the primitive gut tube run?
From the stomatodeum rostrally to the procotdeum caudally
What is the stomatodeum?
What is the proctodeum?
Where does the primitive gut tube have an opening?
At the umbilicus
What is the opening at the umbilicus in the primitive gut tube called?
The vitelline duct
Where does the vitelline duct lead to?
The yolk sac
Draw a diagram of the primitive gut tube
What is the internal lining of the primitive gut tube derived from?
The endoderm (future epithelial linings)
What is the external lining of the primitive gut tube derived from?
Splanchnic mesoderm (future musculature, visceral peritoneum)
What is the primitive gut tube suspended in?
What suspends the primitive gut tube in intraembryonic coelom?
A double layer of splanchnic mesoderm
What are the adult derivates of the foregut?
- Gall bladder
- Duodenum (proximal to entrance of bile duct)
What is the blood supply to the foregut?
What are the adult derivatives of the midgut?
- Duodenum (distal to entrance of bile duct)
- Ascending colon
- Proximal 2/3 transverse colon
What is the blood supply of the midgut?
- Superior mesenteric artery (SMA)
- Superior mesenteric vein
What is the parasympathetic innervation of the midgut?
What is the sympathetic innervation of the midgut?
Superior mesenteric ganglion and plexus
What are the adult derivatives of the hindgut?
- Distal 1/3 of transverse colon
- Descending colon
- Sigmoid colon
- Upper anal canal
- Internal lining of bladder and urethra
What is the blood supply of the hindgut?
- Inferior mesenteric artery (IMA)
- Inferior mesenteric vein (IMV)