Embryology of the foregut Flashcards
where does the primitive gut tube extend to
fro the orophrngeal membrane to the cloacal membrane
what is the mid gut continuous with
the yolk sac at the vitelline duct
what is the epithelial lining derived from
endoderm
what is smooth muscle and connective tissue derived from
surrounding visceral mesoderm
what is the primitive gut suspended by
by the dorsal mesentery from the posterior abdominal wall
what are the borders of the dorsal mesentery
from lower oesophagus to cloaca
what ate the borders of the ventral mesentery
from lower oesophagus to 1st part of duodenum which forms the lesser momentum and falciform ligament
what do villitine arteries give rise to
arteries of the GIT
when does formation of the definitive gut lumen occur and what happens
week 6 - proliferation of the endoderm derived from epithelial lining occludes gut tube
apoptosis of epithelium over next 2 week creates vacuoles - recanalisation
vacuoles coalesce to fully recanalise in gut tube by week 9
what are the 3 types fo abnormal recanalistaion
duplication
incomplete canalisation - stenosis or blockage (atresia)
which part of the GIt is most common to abnormal recanalisation
ileum then duodenum
what are duplication cysts
rare but have high incidence of complications eg bowel obstruction or intussusception
how does the foregut initially develop
gives rise to respiratory diverticulum
separates from RD by forming a tracheosophageal septum - pharynx and oesophagus
what does displacement of the tracheosophegeal spetum do
oesophageal atresia - prevents foetus swelling amniotic fluid and retiring it to the mother through placental circulation
this is polyhydraminos
what does the oesophagus derive from and in what week
week 4 caudal to the lung bud
epithelial lining from endoderm
smooth muscle from mesoderm
skeletal muscles from paraxial mesoderm