Embryology of the GI Tract Flashcards
What is gastrulation?
The formative process by which the 3 germs layers and axial orientation of the embryo is established
What are the 3 germ layers?
Ectoderm, endoderm, mesoderm
During what week of development is the primordial gut formed?
4th
From what part of the primal gut tube does the foregut develop?
The cranial part
The laryngo-tracheal diverticulum develops from what?
The ventral wall of the foregut
What does the trachea-oesophageal septum divide the foregut into?
Trachea and oesophagus
From what parts of the foregut and midgut is the duodenum formed?
The caudal part of the foregut and the cranial part of the midgut
During what week of development does the liver primordium appear?
Middle of the third week
What is formed by ventral outgrowth from the bile duct during development?
The gall bladder and cystic duct
During what week of development are the pancreas and spleen formed?
5th
The development of what part of the GI tract involves the rapid elongation of the gut-tube and its associated mesentery?
Midgut
What part of the primary intestinal loop will become the distal duodenum, jejunum and proximal ileum?
The cephalic part
The caudal part of the primary intestinal loop will become what structures?
Distal ileum, caecum, appendix, ascending colon and proximal 2/3 of the transverse colon
What structures are part of the hindgut?
Distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum and upper part of anal canal
The endoderm of the handgun forms
lining of bladder and urethra
Give a disease of the oesophagus that can arise from abnormal development
Oesophageal atresia
Trachea-oesophageal fistula
What causes incomplete separation of the laryngo-tracheal tube?
Incorrect deviation of the trachea-oesophageal septum
What may arise from abnormal development of the pancreas and cause duodenal stenosis?
Annular pancreas
What is an omphalocele?
Herniation of the abdominal viscera through the umbilicus
What might cause an omphalocele?
Failure of retraction of the herniated loops - liver, stomach or intestinal loops
What is gastroschisis?
Herniation of the abdominal contents directly through the body wall into the amniotic cavity
What can be formed by remnants of the Vitelline duct and what can it cause?
Meckel’s diverticulum
May form fistula or vitalline cyst/ligament
What might result from the incomplete separation of the hindgut from the urogenital sinus by the urorectal septum?
Urorectal fistula
Rectovaginal fistula
Rectoanal atresia
Imperforate anus
