Embryology of the GI tract Flashcards
Define gastrulation
Formation of the trilaminar disc from the bilaminar disc (occurs in week 3)
Time frame: fertilization to implantation
1-6 days
wEEK 2: WHAT HAPPNES?
Formation of th ebilaminar disc, amniotic cavity (epiblast cells) and yolk sac (hypobvlast cells) development
In wk 2: what does the trophoblsatic layer differntiate into?
Synctotrophoblastic and cytotrrophoblastic layers
What gene is trranscriptin for left sidedness? What happens if there is a problem?
PXT 2 - can get things on the oposite side, eg dextrocardia
Week 3.. what happens?
formation of the trilaminar disc, development of endo, ecto and mnesoderm as well as Neurulation and CNS induction
What happens week 3-8?
Organogenesis
What does the embryonic ectoderm form?
CNS, PNS, skin, glands eg mammary/sweat, things on the outside iof the body, hair,
Embryoinic endoderm forms what?
Epithelial lining of
Respiratory system, GIT, glands, liver
(hepatocyte and biliary epithelium), pancreas,
thyroid, parathyroid parenchyma, urinary
bladder etc.
(things with connection to the outside but are on the inside (inner ring of donut))
Embryonic mesoderm forms what?
connective tissue and the dough on the inside of the donut. muscles, bones,
cartilage, dermis, vascular system, urogenital
system except bladder, spleen, liver
mesenchyme, adrenal cortex etc
When is the gut tube formed?
weeks 3-4
Lateral plate mesoderm gives rise to what?
parietal and visceral mesoderm.
How is the amniotic cavity (developing foetus) connected to the yolk sac by week 4?
Vitelline duct
When does the vitelline duct disintergrate?
weeks 12-14
what are the ends of the gut tube?
Oropharyngeal membrane to the Cloacal membrane
How does the dorsal mesoderm suspend the gut tube?
through the dorsal mesentery
What is the signalling pathway of the HOX 1 gene (that tells the mesoderm what to become?)
Sonic Hedgehog (secreted by gut endodermal cells)
What is mesentery?
*Double layers of
peritoneum
*Hangs gut tube from body
wall
*Mesodermal in origin
*Enclose organs
(intraperitoneal organs)
ventral mesentarY region
jUST THE TOP PART, diaphragm to gallbladder
when does the lung bug develop?
Week 4
Whgatseparates te lungs from the oesophagus?
Tracheoesophageal ridge
When does the gut dilate to form stomach?
Week 4
How does it form the greater and lesser curvatures?
rotations. lomgitudinal and antero-posterior axis