Flashcards in Development of the Gut Deck (52)
Foregut goes from
pharynx to proximal 1/2 duodenum
midgut goes from
distal 1/2 duodenum to proximal 2/3 transverse colon
Hindgut goes from
distal 1/3 transverse colon to proximal 2/3 anal canal
How do we start off life?
bi-laminar disc of epiblast and hypoblast
What creates the third layer between ectoderm and endoderm
eventually forms the mouth. At the cranial end. Ectoderm of the stomodeum. Rupture ~week 4
what does ectoderm become?
the gut tract/ anything mucosa
What is mesenchyme?
undifferentiated stem cells
What are the two types of folding in the gut?
Longitudinal and transverse
ectoderm and mesoderm fold laterally and ventrally, which close off endoderm forming a seperate gut tube layer.
endoderm > epithelial lining
mesoderm > supporting structures and SM
outer mesenchymal layer > outer tissue layer
~17-18 days. opening between gut tube and yolk sac draws closed like a drawstring bag.
Divides into foregut, midgut (open to yolk sac) and hindgut
With further folding yolk sac opening gets smaller and smaller and gut sections become more defined.
What are the two transitional regions between endoderm (mucosal) and ectoderm (skin)?
oropharangeal membrane (mouth)
anal membrane (anys)
Eventually forms the anus. At the caudal end, ectoderm of the anal pit. ~ week 8 ruptures.
What is weird about the development of the gut tube lumen?
Initially the gut tube = oatent
As epithelium proliferates, it plugs up the lumen.
~ week 8 recanalization occurs
Arterial supply to FOREGUT
Celiac Trunk located @ T12
Arterial supply to MIDGUT
Superior Mesenteric Artery @ L1
Arterial supply to HINDGUT
Inferior Mesenteric Artery @ L3
Whats interesting about SMA
It goes all the way through the yolk sac and maintains a connection with the umbilical system
Why is the arterial supply of value?
Because it indicates the lymphatics and veins
Is the lungs endoderm or ectoderm, and why?
Endoderm. Because everything that secretes mucus is from endodermal origin.
How are the lungs formed?
Via a respiratory divaticulum, where the lungs bud of the oesophagus, eventually separating.
Starts as small tube immediately caudal to pharynx.
seperates from trachea to form oesophagus.
Rapidly elongates downwards.
What are some forms of oesophagus congenital malformations?
1) Tracheoesophageal Fistula (abnormal connection) = 'punches its way into trachea
2) Tracheoesophageal Atresia (blockage) = end up with blind end, baby starts vomiting up milk
3) Congenital Hiatal hernia= short oesophagus, stomach herniates into thorax, through oesophageal hiatus
What does the stomach sit between
Ventral and dorsal mesogastrium
Stage 1 of stomach formation
Gut tube starts to dilate