Embryology IV: GI development
10/22/2009 Nickalus Khan
Questions (1-63)
1. How is the GI tract separated from the yolk sac?
2. What embryonic layer is the GI tract derived from?
3. What surrounds the GI tract and gives rise to the smooth muscle around the GI tract?
4. What helps seal off GI from yolk sac?
5. Where do the liver buds arise?
6. Where does the foregut arise from?
7. Where does the midgut arise from?
8. Where does the hindgut arise from?
9. What is a mesentery?
10. What suspends the GI tract from the posterior abdominal wall?
11. What are organs called that are surrounded by more than one layer of peritoneum?
12. Where is the ventral mesentery limited to?
13. What is the respiratory diverticulum derived from?
14. What is the artery of the foregut?
15. What divides the trachea and esophagus?
16. What is tracheoesophageal fistula?
17. What is esophageal atresia?
18. What are some signs of tracheoesophageal fistula?
19. How many rotations of the stomach occur to produce its definitive location?
20. How is the omental bursa formed?
21. What is the ventral mesentery formed from?
22. What grows into the septum transversum?
23. What does the septum transversum also form?
24. What are the two origins of the pancreas?
25. What happens as the pancreas is pushed against the dorsal body wall by the leftward
shifting of the stomach and dorsal mesogastrium?
26. What is the greater omentum formed by?
27. Describe the development of the omental bursa.
28. In shortening of the omental bursa what happens to the mesentery of the transverse
colon?
29. What are the derivatives of the dorsal mesentery?
30. What are the derivatives of the ventral mesentery?
31. Describe the formation of the duodenum.
32. How does the gallbladder develop?
33. What is the #1 cause of liver transplant in infants?
34. What does the ventral pancreatic bud come off of?
35. What does the dorsal pancreatic bud come off of?
Embryology IV: GI development
10/22/2009 Nickalus Khan
36. What is the main pancreatic duct formed from?
37. What is annular pancreas?
38. What artery supplies the midgut?
39. Describe the physiological herniation of the midgut.
40. What follows the cephalic and caudal end of the primary intestinal loop?
41. What is a remnant of GI attachment to yolk sac?
42. What does the cephalic limb give rise to?
43. What does the caudal limb give rise to?
44. Does the sup. mesenteric artery re-enter the abdomen prior to the intestinal loop?
45. What axis does the flip of intestines occur along?
46. Where does the physiological invagination of umbilical cord occur?
47. What is omphalocele?
48. What is gastrochisis?
49. What is meckel’s diverticulum?
50. What is a vitelline fistula?
51. What is the difference between stenosis of the GI tract in the foregut vs. midgut?
52. What artery supplies the hindgut?
53. Does the hindgut contain the inf. part of the anal canal?
54. What divides the primary urogenital sinus and the anal canal?
55. What line divides the embryological development of the anal canal?
56. What is rectourethral fistula?
57. What is hirschsprung disease?
End of Class questions:
58. During development of the stomach, the part of the tubular organ originally facing anterior
faces ______ in the definitive organ.
59. What structure divides the ventral mesogastrium into two parts?
60. What event closes the inferior recess of the omental bursa?
61. What membrane covers omphalocele?
62. What structure serves as the axis for midgut rotation?
63. What is the developmental significance of the pectinate line in the anal canal?
Embryology IV: GI development
10/22/2009 Nickalus Khan
Answers:
1. Tubular invagination separates developing yolk sac & lateral body folding eventually pinches off
this tubular invagination to separate it from yolk sac
2. Endoderm
3. Splanchnic mesoderm
4. Head to tail folding
5. Invagination of duodenum into Septum transversum
6. Buccopharyngeal membrane to the first part of duodenum (distal to the liver buds)
7. Part of duodenum just distal to the foregut to the proximal 2/3 of the transverse colon
8. Distal 1/3 of transverse colon to the cloacal membrane
9. Double layer of peritoneum that encloses organs
10. Dorsal mesentery
11. Intraperitoneal
12. Developing caudal end of esophagus, stomach and first part of duodenum
13. Endoderm of the GI tract
14. Celiac trunk
15. Tracheoesophageal septum
16. Opening of esophagus into trachea
17. Blind end of esophagus
18. Polyhydramnios, regurgitation, distended stomach
19. Two: one around longitudinal axis, another anterior rotation “steering wheel movement” upper
part comes down & pyloric region comes up
20. As the dorsal mesogastrium is shifted to the left small vacuoles appear and thin out part of the
dorsal mesogastrium ; this thinning + movement of dorsal mesogastrium makes the omental
bursa
21. Septum transversum which is derived from splanchnic mesoderm between heart and GI tract
22. Liver, has connections one anterior and one posterior (anterior= falciform lig., posterior=lesser
omentum)
23. Central tendon of diaphragm, ventral mesentery
24. Bud off liver, bud off duodenum which then elongate into dorsal mesogastrium
25. Two layers of peritoneum pushed together one disappears and the pancreas is now
retroperitoneal
26. Double fold of dorsal mesogastrium
27. Originally it lies between the greater omentum (two layers of dorsal mesogastrium) in the area
of the transverse colon and small intestines, however as development progresses these two
layers fuse and the omental bursa is shortened accordingly
28. Fuses with the greater omentum
29. Greater omentum, lienorenal lig, sigmoid mesocolon, transverse mesocolon,mesentery proper,
mesoappendix
30. Falciform lig. , lesser omentum
Embryology IV: GI development
10/22/2009 Nickalus Khan
31. Junction of two parts just distal to origin of liver bud, at first duodenum is suspended from
dorsal mesentery as stomach roates it is pushed against post. abdominal wall and becomes
retroperitoneal (similar to pancreas)
32. As a part of invagination of liver
33. Biliary atresia, failure of gallbladder ducts to recanalize can’t convey bile out of liver
34. Liver bud (produces head of pancreas)
35. Duodenum (produces majority of pancreas)
36. Entire part of ventral duct and proximal part of dorsal duct
37. Ventral pancreatic bud splitting and encircling esophagus causing constriction
38. Superior mesenteric a.
39. A forced intestinal loop out through the umbilicus, called primary intestinal loop.
40. Superior mesenteric a.
41. Vitelline duct
42. Duodenum ileum
43. Ileumproximal 2/3 of Transverse colon
44. No, the sup. mesenteric a. enters last
45. Sup. mesenteric a.
46. Primitive umbilical ring
47. Occurs at umbilical ring , bulge in umbilical cord covered by an amnion membrane
48. Occurs at side of umbilical ring, caused by improper lateral folding, not covered by amnion,
umbilical cord is not involved (intestines & other organs developing outside abdominal wall)
49. Remnant of vitelline duct that persists, can become ulcerated and inflamed
50. Connection between umbilicus and intestines, fecal matter protrudes through umbilicus
51. Foregut: vomit contains no bile, Midgut: vomit contains bile ; Both will produce
polyhydramnios, distended stomach
52. Inferior mesenteric a.
53. No, that is an outcropping of ectoderm
54. Urorectal septum
55. Pectinate line, below this line proliferation of mesoderm causes an anal pit, at bottom of this pit
is anal membrane, when this ruptures we have a communication between ectoderm derived
lower anal canal and endoderm (GI tract) derived upper anal canal
56. Communication between hindgut and UG system, feces into urethra
57. Defect in bowel migration no parasympathetic inn.  no peristalsisaccumulation of fecal
mattermegacolon
End of Class Questions
58.
59.
60.
61.
Right
Liver
Fusion of two layers of greater omentum
Amnion
Embryology IV: GI development
10/22/2009 Nickalus Khan
62. Sup. mesenteric a.
63. Below pectinate line formed by anal pit (ectoderm), above is formed by hindgut (endoderm)