Digestive System Development Quiz
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Questions and Answers

Which structures are formed by the differentiation of the intraembryonic mesoderm?

  • Aorta and Inferior Vena Cava
  • Endodermal gut tube and Cloaca
  • Neural tube and Somatopleure
  • Paraxial mesoderm, Intermediate mesoderm, Lateral plate mesoderm (correct)

    • What is the primary function of splanchnic mesoderm in the gastrointestinal system?

  • Development of the pericardial cavity
  • Separation of the coelomic cavities
  • Formation of the epithelium
  • Formation of connective tissue and muscle (correct)

    • What does the allantois develop from in the early stages of embryonic development?

  • An out-pouching of the midgut
  • An out-pouching of the hindgut (correct)
  • A direct connection to the yolk sac
  • An out-pouching of the foregut

    • Which of the following statements is true regarding the vitelline duct?

    <p>It becomes increasingly narrow as the yolk sac atrophies. (D)</p> Signup and view all the answers

    What are the three main components of the intraembryonic coelom as described?

    <p>Pleural, Pericardial, Peritoneal cavities (A)</p> Signup and view all the answers

    What does the somatopleure contribute to during embryonic development?

    <p>Body wall formation (A)</p> Signup and view all the answers

    How is the cloaca eventually divided during development?

    <p>Into the rectum and urogenital sinus (D)</p> Signup and view all the answers

    What is the role of the umbilical vein in adult anatomy?

    <p>It becomes the round ligament of the liver. (D)</p> Signup and view all the answers

    What is formed when the lateral plate mesoderm splits?

    <p>Somatic and Splanchnic mesoderm (A)</p> Signup and view all the answers

    Which structures are found within the caudal free edge of the lesser omentum?

    <p>Bile duct, portal vein, and hepatic arteries. (D)</p> Signup and view all the answers

    What connects the gut tube to the ventral body wall?

    <p>Ventral mesogastrium. (A)</p> Signup and view all the answers

    What happens to the peritoneal cavity after the rotation of the stomach?

    <p>The right cranial cavity is trapped dorsal to the stomach. (D)</p> Signup and view all the answers

    How does the gall bladder connect to the biliary system?

    <p>By the cystic duct leading to the bile duct. (A)</p> Signup and view all the answers

    What is a significant change in the entrance to the omental bursa post-stomach rotation?

    <p>It becomes the epiploic foramen, which is smaller now. (A)</p> Signup and view all the answers

    From which embryological structure does the pancreas develop?

    <p>Two outgrowths, a ventral and a dorsal bud. (A)</p> Signup and view all the answers

    What is the consequence of the vitelline duct remaining attached to the umbilicus?

    <p>It inhibits normal movement of the gut in adults. (B)</p> Signup and view all the answers

    What borders the epiploic foramen dorsally?

    <p>Caudal vena cava. (B)</p> Signup and view all the answers

    Which structure serves as a key landmark during midgut rotation?

    <p>Cecum (A)</p> Signup and view all the answers

    How much does the midgut rotate during its return to the abdominal cavity?

    <p>270° counterclockwise (C)</p> Signup and view all the answers

    What condition results when the midgut does not return from the umbilical cord?

    <p>Omphalocele (D)</p> Signup and view all the answers

    During the development of the midgut, which limb grows more rapidly?

    <p>Proximal limb (B)</p> Signup and view all the answers

    What is often referred to as 'The Mesentery' in the context of midgut development?

    <p>The twisted mesentery attaching jejuno-ileum (A)</p> Signup and view all the answers

    Which developmental abnormality particularly involves intestinal contents lying externally and covered by the amnion?

    <p>Omphalocele (A)</p> Signup and view all the answers

    What happens to the cecum during midgut rotation?

    <p>It first moves to the left and then cranially. (A)</p> Signup and view all the answers

    Flashcards

    Midgut Formation

    The midgut tube forms by the ventral folding of the lateral endoderm.

    Vitelline Duct

    The connection between the digestive tube and the yolk sac.

    Allantois development

    An out-pouching of the hindgut that eventually forms part of the cloaca.

    Intraembryonic Mesoderm layers

    Mesoderm is divided into paraxial, intermediate, and lateral plate mesoderm.

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    Somatopleure

    Fusion of somatic mesoderm and overlying ectoderm, forming the body wall.

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    Splanchnopleure

    Fusion of splanchnic mesoderm and underlying endoderm forming the gut wall.

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    Intraembryonic Coelom

    The cavity between somatic and splanchnic mesoderm, developing into the pleural, pericardial, and peritoneal cavities.

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    Endoderm vs. Splanchnic Mesoderm

    Endoderm forms the epithelial lining of the GI tract, splanchnic mesoderm forms the connective tissue and muscles of the gut wall.

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    Meckel's diverticulum

    A pouch in the ileum, a part of the small intestine, caused by the leftover part of the vitelline duct.

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    Midgut herniation

    The temporary movement of the midgut into the umbilical cord during fetal development.

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    Omphalocele

    A birth defect where the intestines don't return to the abdomen, remaining outside the body.

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    Proximal limb of midgut loop

    The part of the developing midgut loop that becomes the ascending duodenum and jejunum, returning first to the abdominal cavity.

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    Cecum

    Part of the large intestine. A good landmark for observing midgut rotation.

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    Mesentery

    The membrane connecting the intestines to the abdominal wall; contains major blood vessels for supplies.

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    Umbilical Vein

    A remnant of the fetal blood vessel that carried oxygenated blood from the placenta to the fetus. In adults, it becomes a fibrous cord called the round ligament of the liver, located within the falciform ligament.

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    Falciform Ligament

    A peritoneal fold that connects the liver to the ventral body wall. It contains the round ligament of the liver (remnant of the umbilical vein) in its free edge.

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    Lesser Omentum

    A mesentery (double layer of peritoneum) that connects the liver to the stomach and duodenum.

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    What structures are contained within the lesser omentum?

    The lesser omentum contains the bile duct, portal vein, and hepatic arteries. These structures carry blood and bile between the liver and the digestive system.

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    Omental Bursa

    A peritoneal space located behind the stomach and greater omentum. It forms due to the rotation of the stomach during development.

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    Epiploic Foramen

    An opening that connects the main peritoneal cavity to the omental bursa. It is found under the free edge of the lesser omentum.

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    Cystic Duct

    A short duct that connects the gallbladder to the bile duct. It allows bile to flow from the gallbladder into the bile duct.

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    Pancreas Development

    The pancreas develops from two buds of endodermal cells: a ventral and dorsal bud. They eventually fuse to form the mature pancreas.

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    Study Notes

    Digestive System

    • Key Terms: Ventral folding morphogenesis, Vitelline duct, Mesentery, Cloacal membrane, Foregut, Midgut, Hindgut, Hox genes in Gl patterning, Liver, Celiac artery, Cranial mesenteric artery, Caudal mesenteric artery, Stomach, Duodenum, Dorsal mesogastrium, Ventral mesogastrium, Greater omentum, Lesser omentum, Omental bursa, Rumen, Non-glandular fore-stomachs, Colon, Rectum, Cloacal membrane, Urogenital sinus, Urorectal septum, Anal membrane, Meckel's diverticulum, Physiologic umbilical hernia, Umblical hernia, Omphalocele, Imperforate anus/atresia ani, Vascular ring anomalies.

    Learning Objectives

    • Describe the embryonic formation of the early gut tube.
    • Name the embryonic tissues that give rise to the GI tract and its derivatives (e.g., liver).
    • Describe the relationship between the yolk sac and the embryonic gut tube, and identify the connecting structure.
    • Explain basic mechanisms for establishing cranial/caudal regional identity in development.
    • Describe stomach development and how it varies between species.
    • Describe the development of the omentum (greater and lesser) and its associated bursa.
    • Describe liver development and inductive effects from nearby tissues.
    • Identify two reasons why mesenteries are critical to the GI tract.
    • Explain the vascular supply to different parts of the GI tract.
    • Explain the role of physiologic herniation in abdominal organ development.
    • Describe Meckel's diverticulum and related anomalies.
    • Explain how different species' GI tracts develop specialized forms.
    • Explain developmental defects and their clinical presentations.

    Introduction and Review

    • Endoderm initially forms the primitive endoderm lining the yolk sac.
    • Definitive endoderm forms from cells migrating during gastrulation, replacing the hypoblast.
    • Endoderm in the embryo connects to the yolk sac endoderm.
    • Embryo bends and folds due to nervous system growth, creating craniocaudal and lateral folding (ventral folding morphogenesis).

    Mesodermal Layers

    • Intraembryonic mesoderm differentiates into paraxial, intermediate, and lateral plate mesoderm.
    • Lateral plate mesoderm further splits into splanchnic (visceral) and somatic (parietal) mesoderm.
    • Somatic mesoderm fuses with ectoderm to form somatopleure.
    • Splanchnic mesoderm forms gut tube wall; endoderm forms epithelium.

    Gut Tube Development

    • Gut tube develops with a dorsal mesentery.
    • Nerves, blood vessels, and lymphatics run through mesentery.
    • Septum transversum is a mesodermal layer.
    • Septum transversum partially separates developing heart/lungs from abdominal organs.
    • Gut is divided into foregut, midgut, and hindgut sections.

    Midgut

    • Foregut begins at the buccopharyngeal membrane to distal of the liver bud/duodenal papillae.
    • Midgut extends from duodenum distal to liver bud to left colic flexure.
    • Structures of the midgut are supplied by branches of the cranial mesenteric artery.
    • Hindgut extends from left colic flexure to midpoint of anal canal.
    • Hindgut structures are supplied from branches of the caudal mesenteric artery.

    Caudal Foregut

    • Foregut development discussed in relation to pharynx.
    • Proximal foregut includes the esophagus; thoracic structures descend.
    • Diaphragm separates the thorax and forms an opening for esophagus into the abdomen.

    Simple Stomach

    • The stomach initially forms as a dilation of the gut tube.
    • Dorsal surface (greater curvature) grows faster than ventral (lesser curvature).
    • Stomach rotates 90 degrees longitudinally and rotates again 90 degrees around its dorso-ventral axis.
    • Dorsal mesentery becomes the greater omentum; ventral mesentery forms the lesser omentum.

    Ruminant Stomach

    • This stomach has forestomachs (rumen, reticulum, omasum) and one glandular portion (abomasum).
    • Rumen is largest part.
    • Rumen, reticulum, and omasum aid in grinding and digesting food.
    • Abomasum is comparable to a simple stomach's pyloric portion.

    Liver

    • Endoderm (from duodenum) gives rise to the liver.
    • Signals from septum transversum (BMPs) and cardiac mesoderm (FGFs) specify cells.
    • Liver grows into septum transversum, connecting to the duodenum as bile duct.

    Lesser Omentum

    • Mesentery between liver and stomach/duodenum.
    • Includes bile duct, portal vein, hepatic arteries.

    Malformations of the Digestive System

    • Atresia and stenosis (blockage/narrowing of segments).
    • Aganglionosis (absence of autonomic nerves).
    • Rotation defects (e.g., situs inversus).
    • Omphalocele/umbilical hernia (midgut doesn't return).
    • Umbilical hernia (protrusion at the umbilicus).
    • Imperforate Anus (incomplete development).
    • Vascular ring anomalies (constriction of esophagus).

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    Description

    Test your knowledge on the embryonic development of the digestive system. This quiz covers key terms, structures, and mechanisms involved in the formation of the gut tube and its derivatives. Learn about the relationships and identities in the early stages of development.

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