Development of the Gastrointestinal Tract

Questions and Answers

What is the main function of the vitelline duct during embryonic development?

Attachment of the yolk sac to the embryonic gut (correct)

Development of the foregut

Formation of the primitive gut tube

Formation of the urorectal septum

What is the term for the protrusion of the midgut through the umbilical cord during embryonic development?

Midgut rotation

Hindgut development

Umbilical herniation (correct)

Foregut formation

What is the fate of the cloacal membrane during embryonic development?

It forms the urorectal septum

It is absorbed into the primitive gut tube

It gives rise to the urinary and rectal openings (correct)

It forms the vitelline duct

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

Small intestine Signup and view all the answers

What is the term for the abnormalities that occur during the development of the midgut and hindgut?

Congenital anomalies Signup and view all the answers

What is the blood vessel associated with the allantois?

Umbilical artery Signup and view all the answers

What type of mesoderm forms the connective tissue of the lungs and respiratory tract?

Splanchnic mesoderm Signup and view all the answers

What is the term for the process by which the midgut returns to the abdominal cavity after umbilical herniation?

Midgut rotation Signup and view all the answers

What is the result of the failure of the tracheo-oesophageal septum to close?

Atresia of the oesophagus Signup and view all the answers

What is the term for the septum that separates the urinary and rectal openings?

Urorectal septum Signup and view all the answers

What forms from the ventral mesogastrium as a diverticulum of the foregut?

Liver Signup and view all the answers

How many rudiments does the pancreas arise from?

Two Signup and view all the answers

During which week does the stomach rotate to the left?

Fifth week Signup and view all the answers

What is the result of a tracheo-oesophageal fistula?

Communication between the oesophagus and trachea Signup and view all the answers

What forms from the dorsal pancreatic bud?

Dorsal pancreas Signup and view all the answers

When do the ventral and dorsal pancreatic buds fuse?

By the beginning of the sixth week Signup and view all the answers

What structure does the dorsal pancreas form?

Remainder of the pancreas Signup and view all the answers

What is the location of the midgut in the fetal gut tube?

Distal to the hepatic diverticulum Signup and view all the answers

Which of the following is NOT derived from the midgut?

Stomach Signup and view all the answers

What is the process by which the midgut herniates through the umbilical cord?

Umbilical herniation Signup and view all the answers

What is the fate of the cloacal membrane?

It degenerates Signup and view all the answers

What is the blood supply of the structures derived from the midgut?

Superior mesenteric artery Signup and view all the answers

What is the purpose of the learning outcomes of this lecture?

All of the above Signup and view all the answers

What is the ventral pancreas responsible for forming?

Uncinate process Signup and view all the answers

Which of the following structures is derived from the hindgut?

Descending colon Signup and view all the answers

What is the relationship between the hindgut and the allantois?

The hindgut gives rise to the allantois Signup and view all the answers

What is the fate of the membrane separating the hindgut and proctodeum?

It is perforated before birth Signup and view all the answers

What is the blood supply of the structures derived from the hindgut?

Both inferior and superior mesenteric arteries Signup and view all the answers

What is the relationship between the hindgut and the urorectal septum?

The urorectal septum separates the hindgut from the urinary bladder Signup and view all the answers

What is the developmental origin of the superior part of the anal canal?

Hindgut Signup and view all the answers

What is the fate of the allantois during development?

It forms the urinary bladder Signup and view all the answers

What is the relationship between the hindgut and the epithelium of the urinary bladder?

The hindgut gives rise to the epithelium of the urinary bladder Signup and view all the answers

What is the estimated frequency of congenital anomalies of midgut development in live births?

1 in 500 Signup and view all the answers

What is the usual direction of the second phase of rotation of the midgut?

Counter-clockwise Signup and view all the answers

What is the net rotation of the midgut if the second phase of rotation is in a reverse direction?

90 degrees clockwise Signup and view all the answers

What is the location of the duodenum in a non-rotation of the midgut?

In front of the transverse colon Signup and view all the answers

What is the main difference between an omphalocoele and an umbilical hernia?

The timing of the gut's return to the abdominal cavity Signup and view all the answers

What is the frequency of omphalocoele in live births?

1 in 6000 Signup and view all the answers

What is the main characteristic of a gastroschisis?

The protrusion of the gut through a small opening in the anterior abdominal wall Signup and view all the answers

What is the usual location of the opening in a gastroschisis?

Just right of the umbilicus Signup and view all the answers

Study Notes

Development of the GI Tract

The GI tract develops from a primitive gut tube that forms three main divisions: foregut, midgut, and hindgut.

Foregut

The foregut gives rise to the:
- Trachea and lungs (via the tracheo-oesophageal septum)
- Oesophagus
- Stomach
- Liver, gall bladder, and ventral pancreas (from the ventral mesogastrium)
- Dorsal pancreas (from the dorsal pancreatic bud)
Development of the glands of the foregut:
- The liver develops as a diverticulum of the foregut
- The gall bladder and ventral pancreas develop from the liver diverticulum
- The dorsal pancreatic bud appears around day 26, and the ventral pancreatic bud appears less than a day later
- The two pancreatic buds fuse to form a single organ
Development of the pancreas:
- The stomach rotates to the left, and the hepatic duct and ventral pancreas migrate around the foregut
- The ventral pancreas comes into contact with the dorsal pancreas and fuses with it
- The developing liver and stomach expand within the abdominal cavity, and the pancreas comes to lie on the left

Midgut

The midgut gives rise to the:
- Duodenum (distal to the opening of the bile duct)
- Jejunum
- Ileum
- Caecum and appendix
- Ascending colon
- Proximal 2/3rds of the transverse colon
Development of the midgut:
- Umbilical herniation and subsequent mid-gut rotation occur
- The midgut undergoes two phases of rotation: the first 90 degrees counter-clockwise, and the second 180 degrees counter-clockwise
- Failure of the second phase of rotation can result in non-rotation or reversed rotation of the midgut
Congenital anomalies of the midgut:
- Omphalocoele (failure of the gut to return to the abdominal cavity)
- Gastroschisis (protrusion of the gut through a small opening in the anterior abdominal wall, usually right of the umbilicus)

Hindgut

The hindgut gives rise to the:
- Distal 1/3rd of the transverse colon
- Descending colon
- Sigmoid colon
- Rectum
- Superior part of the anal canal
- Epithelium of the urinary bladder and most of the urethra
Development of the hindgut:
- The hindgut also gives rise to the allantois, which forms the fetal bladder and most of the developing urethra
- The proximal part of the allantois duct enlarges to form the fetal bladder
- The hindgut and proctodeum are separated by a membrane that must be perforated before birth

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Description

Learn about the formation of the primitive gut tube, vitelline duct, allantois, and the development of the glan in this lecture on the development of the gastrointestinal tract.