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Z-L7-B123-GIDa(0).pptx

27 Mar 2023
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Z-L7-B123-GIDa(0).pptx

  1. LECTURE SEVEN OVERVIEW (Lecture 7a) Gastrointestinal Tract Development and Malformations © 2020. Dr. Joseph K. Choge, PhD
  2. Development of G.I.T Overview – 1a • Primitive gut, (derived from endodermal yolk sac); Wk4 • Premitive gut extends from bucco-pharyngeal membrane to cloacal membrane* • Communicates with remaining y/sac via vitello- intestinal duct • Foregut; Mid-gut; Hindgut* Assignment 7.1 1. Summarize the G.I.T development:(when, what, where, how, why, which)?* 2. What are the components of the foregut, mid-gut and hindgut?
  3. Development of G.I.T Overview – 1b • G.I.T develops from primitive gut that is derived from the dorsal part of endodermal yolk sac. • Tubular primitive gut:  extends in the median plane from buccopharyngeal membrane at its cranial end to cloacal membrane at its caudal end.  freely communicates with the remaining yolk sac by the vitello-intestinal duct. • The upper one-third part of the esophagus has striated musculature, • Middle one-third has mixed (striated and smooth) musculature, and • Lower one-third has smooth musculature as in the rest of the gut.
  4. Development of G.I.T Overview – 1c Foregut: • Comprises cranial and caudal portions • Cranial portion gives rise to the pharynx • Caudal portion becomes lower oesophagus, stomach and cranial half of duodenum Foregut components: (Summary) • Pharynx, • Trachea • Lower oesophagus, • Stomach, • Duodenum (cranial half)
  5. Development of G.I.T Overview – 1d Midgut Components: • Midgut endoderm gives rise to mucosae of:  Duodenum (2nd half)  Jejunum,  Ileum,  Ascending colon and  Transverse Colon (two thirds of) • Midgut endoderm forms elongating loop resulting in physiological umbilical hernia • Midgut loop rotates anticlockwise; first rotation is 90° as loop enters umbilical cord; further 180° as it returns to abdominal cavity • Occurs 6-10 wks of development
  6. Development of G.I.T Overview – 1e • Hindgut endorm:  Gives rise to mucosae of lower third of transverse colon, descending and sigmoid colon, rectum and upper half of anal canal  Also gives rise to part of the lining of urinary tract • HIndgut Components:  Transverse colon (lower third)  Descending colon  Sigmoid colon  Rectum  Anal Canal (Upper half)
  7. Development of G.I.T Overview – 1f  Development of foregut: • Trachea; Esophagus development*:  Histological composition of adult human G.I.T*  Embryological derivatives of G.I.T epithelia glands and viscera*  Recanalization* • Stomach development* • Liver development* • Gall bladder & Extra-hepatic bile ducts development* • Upper Duodenum development*  Assignment 7.2 1. From histology viewpoint, what are the components of adult human G.I.T? 2. Where are the foregut G.I.T components derived from?* 3. When and how does recanalization occur? 4. Account for the development of the entire foregut.
  8. Development of G.I.T Overview – 1g Clinical Relevance: • Malformations of:  Trachea*  Oesophagus, Pylorus*  Stomach *  Gall bladder and Extra- hepatic ducts *  Liver *  Pancreas * Assignment 7.3 1. Enumerate the clinical abnormalities of the foregut .* 2. Describe their clinical presentations of the foregut malformations* 3. How are the foregut malformations managed?
  9. Summary Foregut Malformations – 1h • Trachea/Oesophagus Malformations:  Tracheo-Oesophageal Fistula (TOF)  Oesophageal stenosis  Oesophageal atresia (also associated with polyhydramnios)  Achalasia cardia (with 'bird peak' deformity) • Trachea/Oesophagus Malformations (Contd):  Dysphagia lusoria  Short oesophagus causing  Congenital hiatal hernia  Oesophageal duplication  Vascular compression of the esophagus
  10. Summary Foregut Malformations – 1j • Congenital Malformations of Stomach:  Congenital Hypertrophic Pyloric Stenosis • Congenital Malformations of liver (Rare): • Minor gross anatomical variations • Gall Bladder (GB) Developmental Anomalies: • Biloped GB • Diverticula GB • Septate GB (due to incomplete recanalization of GB lumen)
  11. Summary Foregut Malformations - 1k • Gall Bladder (GB) Developmental Anomalies (Continued): • Cystic Duct Anomalies: • Biliary Atresia • Intra-hepatic GB • Floating GB (prone to tortion) • Congenital Malformations of Pancreas: • Accessory pancreatic duct • Pancreas divisum
  12. Development of G.I.T Clinical : Foregut Anomalies - 1 • a. Esophageal atresia (Picture opposite; posterior view, which shows that the esophagus terminates blindly in a blunted esophageal pouch (arrow) :  Occurs when the tracheoesophageal septum deviates too far dorsally, causing the esophagus to end as a closed tube.  About 33% of patients with esophageal atresia also have other congenital defects associated with the VATER (vertebral defects, anal atresia, tracheoesophageal fistula, and renal defects) or VACTERL (similar to VATER plus cardiovascular defects and upper limb defects) syndromes.  EA is associated clinically with polyhydramnios (the fetus is unable to swallow amniotic fluid) and a tracheoesophageal fistula.  There is a distal esophageal connection with the trachea at the carina (arrowhead).
  13. Development of G.I.T Clinical : Foregut Anomalies - 2 • b. Esophageal stenosis  (Figure opposite; shows the stratified squamous epithelial lining of the esophagus and submucosal glands)* Note that a portion of the muscular wall contains remnants of cartilage (arrow), which contributes to a stenosis.) • Esophageal stenosis:  Occurs when the lumen of the esophagus is narrowed and usually involves the midesophagus.  The stenosis may be caused by submucosal/muscularis externa hypertrophy, remnants of the tracheal cartilaginous ring within the wall of the esophagus, a membranous diaphragm obstructing the lumen probably due to incomplete recanalization.
  14. Development of G.I.T Clinical : Foregut Anomalies - 3 • c. Esophageal duplication:  (Figure opposite; yhe barium esophagram demonstrates a large intramural duplication cyst in the proximal esophagus (dashed lines). The cyst shows acute angles with the esophageal lumen, indicating its intramural location)  Esophageal duplication: occurs most commonly due to a congenital esophageal cyst, which is usually found (60% of the cases) in the lower esophagus.  Duplication cysts may lie on the posterior aspect of the esophagus, where they protrude into the posterior mediastinum or within the wall of the esophagus (i.e., intramural).
  15. Development of G.I.T Clinical : Foregut Anomalies - 4 • d. Vascular compression of the esophagus  (Figure opposite; the barium esophagram in the same patient reveals an oblique compression of the esophagus (arrow) due to the anomalous right subclavian artery)  The compression occurs due the abnormal origin of the right subclavian artery due to developmental anomalies of the aortic arches  The anomalous right subclavian artery passes from the aortic arch behind the esophagus and may cause dysphagia (“dysphagia lusoria”).
  16. Development of G.I.T Clinical : Foregut Anomalies - 5 • e. Achalasia Cardia: Achalasia occurs due to the loss of ganglion cells in the myenteric plexus (Auerbach) and is characterized by the failure to relax the lower esophageal sphincter, which causes progressive dysphagia and difficulty in swallowing  (Figure opposite; the barium esophagram of the distal esophagus in the figure shows a long, narrowed segment (“bird beak”) of the esophagus secondary to muscular hypertrophy in long-standing achalasia
  17. Development of G.I.T Clinical : Foregut Anomalies - 6a Esophageal (hiatal) Hernia: • Esophageal (hiatal) hernia, is thought to be due to congenital shortness of the esophagus. Upper portions of the stomach are retained in the thorax, and the stomach Is constricted at the level of the diaphragm.
  18. Development of G.I.T Clinical : Foregut Anomalies - 6b  Esophageal Hiatal hernia. • Extreme left figure:  Shows the normal relationship of the gastroesophageal (GE) junction, stomach, esophagus, and diaphragm. • Middle figure:  Shows a sliding hiatal hernia, in which the stomach immediately below the GE junction is seen to prolapse through the diaphragmatic hiatus into the chest. • Extreme right figure:  Shows a paraesophageal hernia in which the cardia or fundus of the stomach prolapses through the diaphragmatic hiatus, leaving the GE junction within the esophageal cavity.
  19. Development of G.I.T Clinical: Foregut Anomalies - 6c Para-Esophageal (Hiatal )hernia A paraesophageal hernia is seen on an upper gastrointestinal radiograph series. Note that the gastroesophageal (GE) junction remains below the diaphragm. (Picture Courtesy of David Y Graham, MD. )
  20. Development of G.I.T Clinical : Foregut Anomalies - 6d Hiatal hernia. This image is a barium radiograph view of a large para- esophageal hernia. GE = gastro- esophageal. (Courtesy of David Y Graham, MD.) Hiatal hernia. This barium radiograph shows a large paraesophageal hernia in which the entire stomach is seen in the chest cavity. (Courtesy of David Y Graham, MD. )
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