54 Liver and Biliary Development in Embryology
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Which structure is primarily supplied by the coeliac trunk?

  • Stomach (correct)
  • Hepatic bud
  • Transverse colon
  • Ileum

    • What is the boundary of the midgut?

  • From the mouth to the beginning of the jejunum
  • From the cloaca to the distal colon
  • From the major duodenal papilla to the proximal two-thirds of the transverse colon (correct)
  • From the oesophagus to the anal canal

    • Which artery supplies the hindgut?

  • Hepatic artery
  • Coeliac trunk
  • Inferior mesenteric artery (correct)
  • Superior mesenteric artery

    • What is an example of a vitelline duct abnormality?

    <p>Meckel’s diverticulum</p> Signup and view all the answers

    Which of the following correctly describes the midgut derivatives?

    <p>Proximal two-thirds of transverse colon, caecum, and appendix</p> Signup and view all the answers

    What common condition can an inflamed Meckel’s diverticulum be misdiagnosed as?

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

    The area supplied by the superior mesenteric artery includes which part of the intestine?

    <p>Distal duodenum and jejunum</p> Signup and view all the answers

    What is a characteristic feature of Meckel’s diverticulum?

    <p>Obeys the 'Rule of 2'</p> Signup and view all the answers

    What is the approximate percentage of body weight the liver accounts for at the 10th week of gestation?

    <p>10%</p> Signup and view all the answers

    Which structure is formed by the caudal offshoot from the liver bud?

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

    At what week does bile formation begin during liver development?

    <p>Week 12</p> Signup and view all the answers

    What is a possible outcome if the proximal part of the dorsal pancreatic duct is obliterated?

    <p>Formation of an accessory pancreatic duct</p> Signup and view all the answers

    What congenital abnormality occurs when one half of a bilobed ventral pancreatic bud constricts the duodenum?

    <p>Annular pancreas</p> Signup and view all the answers

    Which congenital condition of the biliary tree can lead to severe liver dysfunction in neonates?

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

    During which week of gestation does haematopoiesis begin in the liver?

    <p>Week 6</p> Signup and view all the answers

    What anatomical change occurs to the common bile duct as the liver and stomach grow?

    <p>It moves behind the duodenum to enter from the left side</p> Signup and view all the answers

    What is the primary function of the liver during early embryonic development?

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

    What structure is formed from the connection between the liver bud and foregut?

    <p>Common bile duct</p> Signup and view all the answers

    What is the major site of pre-natal haematopoiesis in the embryo?

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

    What anatomical structure does the cranial surface of the liver give rise to?

    <p>Central tendon of diaphragm</p> Signup and view all the answers

    At which week of gestation does the gallbladder and cystic duct form?

    <p>Week 10</p> Signup and view all the answers

    What complication arises if the common bile duct (CBD) does not recanalize properly?

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

    What is the consequence of the dorsal pancreatic duct being obliterated?

    <p>Development of accessory pancreatic duct</p> Signup and view all the answers

    How does the stomach's rotation affect the common bile duct during development?

    <p>Relocates CBD behind the duodenum</p> Signup and view all the answers

    What condition is characterized by a split ventral pancreatic bud surrounding the duodenum?

    <p>Annular pancreas</p> Signup and view all the answers

    When does bile formation begin in the developing liver?

    <p>Week 12</p> Signup and view all the answers

    Which surface of the liver is never covered by peritoneum?

    <p>Cranial surface</p> Signup and view all the answers

    What abnormality may result from the persistence of the vitelline duct?

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

    From which embryonic structure does the respiratory diverticle originate?

    <p>Pharyngeal gut</p> Signup and view all the answers

    Which artery supplies the area from the major duodenal papilla to the proximal two-thirds of the transverse colon?

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

    What is one of the clinical correlates associated with vitelline duct abnormalities?

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

    Which segment of the gastrointestinal tract is primarily supplied by the inferior mesenteric artery?

    <p>Splenic flexure</p> Signup and view all the answers

    In embryonic development, which portion of the gut does the coeliac trunk supply?

    <p>Foregut and derivatives</p> Signup and view all the answers

    What common presentation can occur due to an inflamed Meckel's diverticulum?

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

    Which of the following structures is manipulated during the embryologic development of the foregut?

    <p>Respiratory diverticle</p> Signup and view all the answers

    What is the significance of the 'Rule of 2' related to Meckel's diverticulum?

    <p>It indicates the frequency of occurrence</p> Signup and view all the answers

    What congenital anomaly can result from improper midgut rotation during embryonic development?

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

    Which of the following statements about Meckel's diverticulum is true?

    <p>It is associated with a risk of appendicitis.</p> Signup and view all the answers

    What type of body wall defect is characterized by visceral organs being located outside the abdominal cavity?

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

    What clinical correlate is associated with abnormalities in gut rotation?

    <p>Non-rotation of the midgut</p> Signup and view all the answers

    Which of the following is a potential consequence of abnormal rotation during embryological development?

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

    How does the development of the pancreas occur?

    <p>From two separate buds that fuse to form one structure</p> Signup and view all the answers

    What role does the liver play during embryonic development?

    <p>It serves as a major site for blood cell formation</p> Signup and view all the answers

    Which congenital abnormality is characterized by the complete obstruction of the biliary tree?

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

    What is a potential consequence of the abnormal persistence of the vitelline duct?

    <p>Creation of Meckel's diverticulum</p> Signup and view all the answers

    At what stage does the liver bud begin to differentiate into the liver and gallbladder?

    <p>At the twelfth week of gestation</p> Signup and view all the answers

    What primary structures are developed from the midgut?

    <p>Small intestine and parts of the colon</p> Signup and view all the answers

    Which artery is primarily responsible for supplying the foregut?

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

    When does the major site of haematopoiesis transition to the liver during embryonic development?

    <p>Starting at 6 weeks after fertilization</p> Signup and view all the answers

    Study Notes

    Liver Development

    • Liver development begins during the 4th week of gestation.
    • Liver bud is large and accounts for 10% of body weight at the 10th week of gestation.
    • At birth, the liver accounts for 5% of body weight.
    • Haematopoiesis (production of blood cells) starts in the liver around the 6th week of gestation.
    • Liver is a major site for pre-natal haematopoiesis.
    • Bile formation starts in the liver around the 12th week.

    Gallbladder & Biliary Tract Development

    • Gallbladder and cystic duct develop from a caudal outgrowth of the liver bud.
    • The connection between the liver bud and foregut narrows to become the common bile duct (CBD).
    • CBD lumen initially obliterates and then recanalizes.
    • Initially the CBD is ventral to the duodenum.
    • As the stomach rotates and mesenteries move, the liver shifts rightwards and the CBD moves behind the duodenum to enter from the left side.

    Clinical Correlates - Liver & Biliary Tract

    • Accessory hepatic ducts can occur.
    • Gallbladder duplication can occur.
    • Biliary atresia can occur.

    Pancreas Development

    • Pancreas forms as 2 separate endothelial buds from the foregut.
    • Dorsal bud, at the end of the foregut, appears at the start of the 4th week.
    • Ventral bud appears a few days later, from the liver bud.

    Pancreas Development

    • Proximal part of the dorsal pancreatic duct may be obliterated or persist as the accessory pancreatic duct.
    • The main pancreatic duct is formed by the distal part of the dorsal pancreatic duct and the entire ventral pancreatic duct.

    Clinical Correlate - Pancreas

    • Annular pancreas is a rare anomaly occurring in 1/20,000 births.
    • It develops when the bilobed (split) ventral pancreatic bud moves around the duodenum, constricting it.
    • Symptoms depend upon the degree of stricture and may range from non-bilious to bilious vomiting.

    Midgut

    • The midgut is the portion of the gut tube that extends from the major duodenal papilla to the proximal 2/3rd of the transverse colon.
    • The midgut is supplied by the superior mesenteric artery.

    Midgut Derivatives

    • The midgut forms the distal duodenum, jejunum, ileum, caecum, appendix, ascending colon, and the proximal 2/3rd of the transverse colon.

    Midgut Development

    • Involves a process called physiologic herniation and rotation.
    • Midgut herniates out of the abdomen into the umbilical cord during the 6th week of gestation.
    • During the 10th week, the midgut rotates 270 degrees counter-clockwise.
    • The midgut returns to the abdomen and is fixed in its definitive position by the 10th week.

    Clinical Correlates- Midgut

    • Omphalocele - abdominal wall defect where the midgut fails to return to the abdomen at the end of the 10th week.
    • Gastroschisis - abdominal wall defect where a hole allows the midgut to protrude from the abdomen, not covered with a sac, usually to the right of the umbilicus.

    ### Clinical Correlates - Vitelline Duct

    • Vitelline duct is a connection between the yolk sac and the midgut.
    • Vitelline duct normally obliterates soon after birth.
    • Vitelline duct abnormalities present in neonates and adults:
      • Enterocystoma/Vitelline cyst - remnant of the yolk sac may persist, causing a cyst.
      • Meckel's diverticulum - the yolk sac may persist and form a pouch-like structure attached to the small intestine.
        - Vitelline fistula - a tract that remains open between the small intestine and the umbilical cord.

    Clinical Notes - Meckel's Diverticulum

    • May cause intestinal obstruction, bleeding, or inflammation.
    • Can be misdiagnosed as appendicitis.
    • Meckel's diverticulum follows the "Rule of 2":
      • 2% of the population has Meckel's diverticulum.
      • Found 2 feet from the ileocecal valve.
      • Twice as common in males.
      • 2% of cases show symptoms.

    Liver Development

    • Liver is large and heavy during the 10th week of gestation, representing about 10% of body weight.
    • At birth, liver is 5% of body weight.
    • Liver performs hematopoiesis around 6 weeks after fertilization, and it is a major site for prenatal hematopoiesis.
    • Bile formation begins around the 12th week of development.
    • The visceral peritoneum forms around the surface of the liver excluding the cranial surface.
    • The septum transversum section in contact with the cranial surface of the liver forms the central tendon of the diaphragm.
    • The bare area of the liver is not covered by peritoneum, as it faces the future diaphragm.

    Gallbladder and Biliary Tract Development

    • Develops as a caudal offshoot from the liver bud
    • Gallbladder and cystic duct are formed from this offshoot.
    • The connection between the liver bud and foregut narrows to form the common bile duct (CBD).
    • CBD originally resides ventral to the duodenum, but moves behind it after the stomach rotates.
    • The lumen of CBD obliterates and then recanalizes, similar to the duodenum.

    Pancreas Development

    • The pancreas develops from two separate endothelial buds originating from the foregut.
    • The dorsal bud appears at the end of the foregut around the start of the 4th week.
    • The ventral bud develops a few days later from the liver bud.
    • The proximal part of the dorsal pancreatic duct either obliterates or persists as an accessory pancreatic duct.
    • The main pancreatic duct forms from the distal part of the dorsal pancreatic duct and the entire ventral pancreatic duct.

    Annular Pancreas

    • Annular pancreas occurs in 1/20,000 individuals and is characterized by a bilobed ventral pancreatic bud that splits.
    • One half moves anterior, and the other posterior to the duodenum, surrounding and constricting it.
    • Symptomatic presentation depends on the degree of stricture, ranging from non-bilious to bilious vomiting.
    • Individuals with annular pancreas may have other congenital or neonatal conditions.

    Midgut

    • The midgut is supplied by the superior mesenteric artery.
    • The midgut is the part of the gut tube that extends from the major duodenal papilla to the proximal 2/3 of the transverse colon.
    • Key structures supplied by the superior mesenteric artery include the distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and the transverse colon near the splenic flexure.

    Vitelline Duct

    • The vitelline duct is a connection between the midgut and yolk sac during embryonic development.
    • It plays a role in midgut development.
    • Abnormalities of the vitelline duct can lead to various conditions:
      • Enterocystoma/Vitelline cyst: A cyst formed from the vitelline duct.
      • Meckel’s/Ileal diverticulum: A pouch-like protrusion from the ileum.
      • Vitelline fistula: An abnormal connection between the ileum and the outside of the body.

    Clinical Vignette

    • The case described in the vignette presents as an omphalocele, a body wall defect where abdominal organs protrude through the umbilicus.

    Clinical Correlates

    • Biliary Atresia: A condition where the bile ducts do not develop properly, resulting in blockage of bile flow.
    • Body Wall Defects: Omphalocele (abdominal contents protrude through the umbilicus) and gastroschisis (abdominal contents protrude through a defect in the abdominal wall).
    • Meckel’s Diverticulum: A pouch-like protrusion from the ileum, containing remnants of the vitelline duct.
    • Rule of 2: Meckel’s diverticulum follows the "Rule of 2," meaning it is typically found 2 feet from the ileocecal valve, 2 inches in length, and 2% of the population has it.

    Hindgut

    • The hindgut is the part of the gut tube that extends from the splenic flexure of the colon to the upper anal canal.
    • It is supplied by the inferior mesenteric artery.

    Foregut

    • The foregut stretches from the pharynx to the major duodenal papilla.
    • It is supplied by the celiac trunk.
    • It gives rise to the esophagus, stomach, most of the duodenum, pancreas, liver, and gallbladder.

    Liver Development

    • Forms from the foregut
    • Liver bud differentiates into the liver and gallbladder
    • Begins as a large structure, accounting for significant percentage of body weight during gestation
    • Bile formation starts around the 12th week

    Pancreas Development

    • Develops from two separate endothelial buds (ventral and dorsal) from the foregut
    • Main pancreatic duct formed from both dorsal and ventral components

    Haematopoiesis

    • Liver serves as a major site for haematopoiesis (blood cell formation) during embryonic development
    • Process begins around six weeks after fertilization

    Midgut Development

    • Midgut undergoes physiological herniation and rotation
    • Structures formed from the midgut:
      • Small intestine
      • Parts of the colon
    • Abnormal midgut rotation can lead to:
      • Volvulus
      • Non-rotation

    Vitelline Duct

    • Plays a role in midgut development
    • Its abnormal persistence can lead to:
      • Meckel's diverticulum
      • Vitelline fistula

    Congenital Abnormalities

    • Biliary atresia
    • Annular pancreas
    • Duplication of the gallbladder

    Clinical Correlates

    • Body wall defects:
      • Omphalocele
      • Gastroschisis
    • Meckel's diverticulum:
      • High prevalence
      • Associated complications, such as appendicitis
    • Gut rotation defects:
      • Potential consequences of abnormal rotation

    Blood Supply to the GI Tract

    • Foregut:
      • Supplied by the celiac trunk
    • Midgut:
      • Supplied by the superior mesenteric artery

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    Description

    This quiz covers the development of the liver and biliary tract during embryonic gestation. It includes key stages from the formation of the liver bud to the changes in the common bile duct. Test your knowledge of embryological development with this engaging quiz.

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