Development of the Gut Tube and Esophageal Atresia
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Questions and Answers

What typically accompanies esophageal atresia in newborns?

  • Duodenal atresia
  • Tracheoesophageal fistula (correct)
  • Congenital diaphragmatic hernia
  • Pneumothorax

    • Which condition occurs when the esophagus fails to recanalize?

  • Esophageal stenosis (correct)
  • Tracheoesophageal fistula
  • Congenital hiatal hernia
  • Esophageal atresia

    • What prenatal condition is usually associated with both esophageal atresia and stenosis?

  • Placenta previa
  • Polyhydramnios (correct)
  • Amniotic band syndrome
  • Oligohydramnios

    • How does a congenital hiatal hernia occur?

    <p>Failure of esophagus to grow in length</p> Signup and view all the answers

    What happens to the stomach during early development?

    <p>It undergoes a 90° rotation</p> Signup and view all the answers

    What is primarily formed from endoderm during the development of the primitive gut tube?

    <p>Mucosal epithelium</p> Signup and view all the answers

    Which structure primarily derives from mesoderm in the developing gut tube?

    <p>Muscularis externa</p> Signup and view all the answers

    Which arteries supply the foregut derivatives in the abdomen?

    <p>Celiac artery</p> Signup and view all the answers

    What does the posterior intestinal portal ultimately form in the embryo's gut development?

    <p>Hindgut</p> Signup and view all the answers

    Which of the following organs is NOT derived from the foregut?

    <p>Cecum</p> Signup and view all the answers

    What type of mesoderm surrounds the gut tube during its development?

    <p>Visceral (splanchnic) mesoderm</p> Signup and view all the answers

    Which structure is part of the midgut derivatives?

    <p>Appendix</p> Signup and view all the answers

    What role do cranio-caudal and lateral folding play in the development of the gut tube?

    <p>They draw the gut tube's openings closed.</p> Signup and view all the answers

    What mechanism is primarily responsible for the concentric layering of the gut tube?

    <p>Sonic Hedgehog (SHH) expression in the endoderm</p> Signup and view all the answers

    What occurs around the 5th week of development regarding the gut tube?

    <p>Endoderm temporarily occludes the lumen</p> Signup and view all the answers

    Which mesenteric structure is associated with the stomach?

    <p>Greater omentum</p> Signup and view all the answers

    What happens to the SHH expression later in development?

    <p>It disappears, allowing development of smooth muscle</p> Signup and view all the answers

    Which of the following structures is NOT made from mesentery?

    <p>Thoracic esophagus</p> Signup and view all the answers

    What is the outcome of errors in the occlusion and re-canalization process of the gut tube?

    <p>Stenosis or outright occlusion</p> Signup and view all the answers

    What structures are formed by the tracheoesophageal folds during the development of the foregut?

    <p>Esophagus and trachea</p> Signup and view all the answers

    What does the term 'secondarily retroperitoneal' refer to in the context of the GI tract?

    <p>Organs applied against the body wall during development</p> Signup and view all the answers

    What is the primary consequence of differential growth on the left and right sides of the stomach?

    <p>Establishment of greater and lesser curvatures</p> Signup and view all the answers

    Hypertrophic pyloric stenosis is most commonly characterized by which symptom?

    <p>Forceful, non-bilious vomiting</p> Signup and view all the answers

    Which factor contributes to the formation of the pyloric sphincter?

    <p>Genetic factors affecting smooth muscle growth</p> Signup and view all the answers

    What is the relationship between the liver and the septum transversum?

    <p>Signals from the septum transversum induce liver formation from adjacent endoderm</p> Signup and view all the answers

    What arises from the caudal end of the foregut during pancreas development?

    <p>Ventral and dorsal pancreatic buds</p> Signup and view all the answers

    Which statement correctly describes the structure of the adult liver?

    <p>Consists of plates of hepatocytes surrounded by sinusoidal vessels</p> Signup and view all the answers

    What is a characteristic feature of the endocrine pancreas?

    <p>Forms discrete islands of endocrine tissue within the parenchyma</p> Signup and view all the answers

    What is typically observed in infants with hypertrophic pyloric stenosis?

    <p>Palpable knot at the right costal margin</p> Signup and view all the answers

    What condition can result from inadequate mesoderm generation during gastrulation?

    <p>Anal atresia</p> Signup and view all the answers

    Which neural crest cell migration failure results in an aganglionic segment of the gut?

    <p>Failure of sacral and vagal neural crest cells</p> Signup and view all the answers

    What is the primary complication of an aganglionic segment of the colon?

    <p>Distended abdomen and obstruction</p> Signup and view all the answers

    In which part of the colon is Hirschsprung disease most commonly found?

    <p>Sigmoid colon</p> Signup and view all the answers

    What is the main function of the submucosal and myenteric plexuses?

    <p>Allowing local relaxation of the gut wall</p> Signup and view all the answers

    What is the origin of the uncinate process of the pancreas?

    <p>Ventral pancreatic bud</p> Signup and view all the answers

    Which artery serves the proximal duodenum?

    <p>Superior pancreaticoduodenal artery</p> Signup and view all the answers

    What condition may arise from the failure to recanalize the duodenum during development?

    <p>Stenosis or atresia</p> Signup and view all the answers

    Which part of the GI tract is formed by the cranial loop of the U-shaped loop during development?

    <p>Jejunum and upper part of ileum</p> Signup and view all the answers

    What happens to the duodenum and pancreas during gut tube rotation?

    <p>They become secondarily retroperitoneal</p> Signup and view all the answers

    What is a possible result of failure to obliterate the vitelline duct?

    <p>Meckel's diverticula</p> Signup and view all the answers

    From which part of the midgut does the distal duodenum arise?

    <p>Cranial most portion</p> Signup and view all the answers

    What structure is an elongated remnant of the yolk sac that becomes obliterated during development?

    <p>Vitelline duct</p> Signup and view all the answers

    Study Notes

    Development of Endodermal Derivatives

    • The gut tube forms from endoderm lining the yolk sac, enveloped by developing coelom.
    • Cranial and caudal folding apply somatic mesoderm to the body wall (parietal peritoneum) and visceral mesoderm wraps around the gut tube, creating mesenteries.
    • Mesoderm contributes to gut tube wall.
    • Nerves and neurons originate from neural crest.
    • Endoderm forms mucosal epithelium, mucosal glands, submucosal glands of the GI tract.
    • Mesoderm forms lamina propria, muscularis mucosae, submucosal connective tissue, blood vessels, muscularis externa, adventitia/serosa.
    • Neural crest forms neurons and nerves of the submucosal and myenteric plexuses.

    Gut Tube Regions and Refinement

    • Cranio-caudal and lateral folding form anterior/cranial and posterior/caudal intestinal portals.
    • Foregut and hindgut form from these portals; the midgut remains open to the yolk sac.
    • Yolk sac connection to the gut shrinks as the embryo develops.
    • Foregut derivatives include trachea, lungs, esophagus, stomach, liver, gallbladder, bile duct, pancreas, upper duodenum.
    • Midgut derivatives include lower duodenum, jejunum, ileum, cecum, appendix, ascending colon, proximal 3 of transverse colon.
    • Hindgut derivatives include distal transverse colon, descending colon, sigmoid colon, rectum, upper anal canal, urogenital sinus.
    • Gut regions are defined by arterial supply: foregut by branches of the celiac artery, midgut by branches of the superior mesenteric artery, and hindgut by branches of the inferior mesenteric artery.

    Cranio-caudal Patterning of the Gut Tube

    • HOX genes determine regions of the gut tube (lung, esophagus, stomach).
    • Sonic Hedgehog (SHH) in endoderm inhibits smooth muscle and neuron differentiation near the endoderm.
    • Higher SHH concentration allows differentiation in external layers.
    • Later development allows smooth muscle in the muscularis mucosae and neurons in the submucosal plexus.
    • Gut tube lumen occlusion (5th week) followed by re-canalization (9th week) throughout the tube.
    • Errors in this process may cause stenosis.

    Radial Patterning of the Gut Tube

    • Concentric layering of the gut tube is due to SHH expression
    • SHH inhibits smooth muscle and neuronal differentiation near the endoderm.
    • SHH concentration decreases farther away allowing smooth muscle and neuron differentiation.
    • Occlusion and recanalization affect the esophageal and anal region.

    Clinical Considerations

    • Esophageal atresia: Failure of tracheoesophageal ridges to separate esophagus and trachea.
    • Symptoms include aspiration pneumonia (gut contents/contaminants entering lungs).
    • Typically associated with polyhydramnios (excess amniotic fluid).
    • Esophageal stenosis: Failure of recanalization of the esophagus leads to narrowing.
    • Symptoms include regurgitation, and potentially no tracheoesophageal fistula.
    • Congenital hiatal hernia: Inguinal hernia in diaphragm.
    • Incomplete growth of the esophagus and allows the stomach to form into the esophageal hiatus in diaphragm, causing a hiatal hernia.

    Stomach

    • Stomach rotates 90˚ during development
    • Left side moves ventrally; right side moves dorsally.
    • Greater and lesser curvatures develop due to differential growth.
    • Pyloric sphincter (smooth muscle) forms at the caudal end of the stomach.

    Liver

    • The liver develops from the ventral foregut endoderm, close to the septum transversum.
    • The parenchyma is composed of hepatocytes, and branched bile ducts and is surrounded by vascular sinusoids (mesoderm derived).

    Pancreas

    • Two outgrowths from the foregut: ventral and dorsal pancreatic buds.
    • Exocrine pancreas develops from the endodermal lining.
    • Endocrine pancreas (islets of Langerhans) develop from stem cells that form in the areas of the duct branch points.
    • Rotation causes the merging of the ventral and dorsal buds into a single pancreas.

    Proximal or Upper Duodenum

    • Arises from caudal part of foregut
    • Served by branches of the superior pancreaticoduodenal artery.
    • Becomes secondarily retroperitoneal due to gut rotation.

    Distal or Lower Duodenum

    • Arises from cranial part of midgut.
    • Served by branches of the inferior pancreaticoduodenal artery.
    • Becomes secondarily retroperitoneal due to gut rotation.

    Jejunum, Ileum, Cecum, Appendix, Ascending Colon, Proximal 2/3 of Transverse Colon

    • Rapid elongation of the midgut forms a U-shaped loop that herniates into the umbilicus.
    • The loop contains the future jejunum, ileum, cecum, appendix, ascending colon and proximal two-thirds of transverse colon.
    • The appendix usually points caudally.
    • The loop rotates 90 degrees counterclockwise.
    • Vitelline duct connects to the yolk sac; obliteration is normal; failure leads to complications (Meckel's diverticulum, vitelline cyst, or vitelline fistula).

    Derivatives of the Hindgut

    • Includes distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, and upper anal canal.
    • Hindgut ends in the cloaca (a common chamber with the urogenital tract).
    • Septa divide the cloaca into the urogenital sinus and the rectoanal canal.
    • Failure of the cloacal membrane to close or the failure of the cloaca to divide leads to anatomical abnormalities such as imperforate anus.
    • Hindgut is innervated by vagal and sacral neural crest cells.

    Clinical Considerations

    • Hypertrophic pyloric stenosis: Overdeveloped pyloric sphincter.
    • Hirschsprung disease: Absence of ganglion cells in a region of the distal colon and rectum causes obstruction.

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    Development of Endodermal Derivatives PDF

    Description

    This quiz explores critical concepts related to the development of the gut tube and associated conditions such as esophageal atresia. Questions cover embryonic structures, the roles of different germ layers, and vascular supply to the foregut. Test your understanding of key developmental processes in embryology.

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