Endoderm – how to make a gut tube
From flat sheet to tube
Lateral plate mesoderm splits into parietal and visceral mesoderm, giving rise to the coelomic cavity,
which allows the gut tube to form - lateral folding
The flat sheet undergoes folds, movements and rotations to allow the endoderm to become an
internal gut tube
FoxA2 is a transcription factor that is expressed in all endoderm cells – allows labelling of endoderm
on its path to the gut tube (can see it happening)
At the posterior end of the embryo, the posterior intestinal portal forms – first form of a tube
Longitudinal folding
Brings gut tube into vicinity of mesodermal and ectodermal structures – juxtaposition of gut tube
with other tissues and organs, permits inductive events – other tissues direct or stimulate the
development of gut associated organs
Creates the anterior and posterior intestinal portals (foregut and hindgut)
The cardiac region is brought to the ventral side of the developing gut tube
Direct contact of ectoderm and endoderm at oropharyngeal membrane (future mouth) and cloacal
membrane (future anus)
Midgut opening to the yolk sac progressively narrows to form the umbilical cord
Gut associated organs begin to form as buds from the endoderm (thyroid, lung, liver, pancreas)
Celiac artery supplies foregut, superior mesenteric artery supplies midgut, inferior mesenteric artery
supplies hindgut
From flat sheet to tube
Lateral plate mesoderm splits into parietal and visceral mesoderm, giving rise to the coelomic cavity,
which allows the gut tube to form - lateral folding
The flat sheet undergoes folds, movements and rotations to allow the endoderm to become an
internal gut tube
FoxA2 is a transcription factor that is expressed in all endoderm cells – allows labelling of endoderm
on its path to the gut tube (can see it happening)
At the posterior end of the embryo, the posterior intestinal portal forms – first form of a tube
Longitudinal folding
Brings gut tube into vicinity of mesodermal and ectodermal structures – juxtaposition of gut tube
with other tissues and organs, permits inductive events – other tissues direct or stimulate the
development of gut associated organs
Creates the anterior and posterior intestinal portals (foregut and hindgut)
The cardiac region is brought to the ventral side of the developing gut tube
Direct contact of ectoderm and endoderm at oropharyngeal membrane (future mouth) and cloacal
membrane (future anus)
Midgut opening to the yolk sac progressively narrows to form the umbilical cord
Gut associated organs begin to form as buds from the endoderm (thyroid, lung, liver, pancreas)
Celiac artery supplies foregut, superior mesenteric artery supplies midgut, inferior mesenteric artery
supplies hindgut
