Development of Mesentery and Pancreas

Mesentery is a double fold of the peritoneum. It carries neurovascular bundles, which have Nerves, Arteries, veins, and Lymphatic Ducts.

Transverse Section of The Abdomen Region

Vertebrae are present in the posterior region. The Colon is the gut tube suspended in the peritoneal cavity. The peritoneum present in the body wall is called the parietal peritoneum, and the peritoneum covering the colon is called the visceral peritoneum.

A peritoneal cavity is present between the two peritoneal layers. The colon is suspended in the peritoneal cavity. The double fold of the peritoneum is called the mesentery. It carries the neurovascular bundles.

Mesenteric Layers

Mesentery carries blood vessels from the aorta to the gut tube. At the posterior abdominal wall, the aorta, which gives arteries to the gut tube, is present. In the posterior abdominal wall, the vertebral body called lumbar vertebrae is present. The peritoneum covers the body wall and the viscera. The Peripheral parietal peritoneum covers the body wall.

Viscera is also present inside the gut tube. The Gut tube is covered by the visceral peritoneum, and the space between them is called the peritoneal cavity, as discussed earlier. The Gut tube is suspended in the peritoneal cavity. The aorta, located in the posterior abdominal wall, sends the artery to the gut tube in front of the vertebrae. This artery is carried by a double fold of peritoneum known as the mesentery. If the mesentery is attached to the posterior abdominal wall, it is called dorsal mesentery.

If the peritoneum is attached to the anterior abdominal wall of the abdominal cavity, it is known as ventral mesentery, and the mesentery connecting the gut tube to the anterior abdominal wall is called ventral mesentery.

The mesentery connecting the gut tube to the posterior abdominal wall is the dorsal mesentery. The Gut Tube is the axis, and the mesentery in front of the gut tube is

ventral mesentery. Mesentery has various divisions, like

• Meso enteron (Attaching to the intestine)
• Mesogastrium (Attaching to the stomach)
• Meso duodenum (Attaching to the duodenum)
• Mesoappendix (Attaching to the vermiform appendix)
• Mesocolon (Attaching to the colon)

The Sagittal Section of The Mesentery

The gut tube axis begins with the esophagus, and after that, there is the stomach. This stomach will further continue with the duodenum. The double fold of the peritoneum will be attached to the anterior abdominal wall, which is known as ventral mesentery. If it is attached to the stomach, it is known as the ventral mesogastrium. As the peritoneum attaches to the posterior abdominal wall, it is known as dorsal mesentery. When it is attached to the stomach, it is known as the dorsal mesogastrium.

The lesser curvature of the stomach is present in the anterior region. The greater curvature of the stomach is present in the posterior region. As the stomach rotates, the lesser curvature goes to the right side, and the greater curvature comes to the left side.

The liver develops in the ventral mesentery. The spleen develops in the dorsal mesentery. Pancreas develops both in the ventral and dorsal mesentery. The head of the pancreas develops in the ventral mesentery. The body and the tail of the pancreas develop in the dorsal Mesentery. The anterior abdominal wall of the mesentery has an opening called the umbilicus, through which the midgut is herniating. It is known as the physiological umbilical hernia. The gut tube is coming out of the umbilicus to become a content of the umbilical cord temporarily. In later stages, it will regress. On the posterior abdominal wall, the abdominal aorta is present. This abdominal aorta will give the anterior branches. It gives the anterior branches to the foregut, which is called the coeliac trunk. It gives the anterior branches to the hindgut, which is called the inferior mesenteric artery. The aorta has anterior branches because the gut tube starts developing in the midline of the body in front of the aorta. 

The head of the pancreas will be developed in the ventral Mesentery. The anterior abdominal wall has an umbilical opening. The Left umbilical vein passes to the liver through the umbilical opening. In adults, the left umbilical vein becomes the ligamentum teres of the liver. The left umbilical vein carries oxygenated blood into the liver (in fetal circulation). The left umbilical vein or ligamentum teres is carried by a double-fold peritoneum called the falciform ligament to the liver.

If it passes more superiorly, it is called the coronary ligament of the liver. If it passes more posteriorly, it is called the lesser omentum, If it attaches to the lesser curvature of the stomach. All the ligaments of the liver are derived from the septum transversum will forms the central tendon of the diaphragm. Septum transversum forms the central tendon of the diaphragm, it also forms the ventral mesentery of the stomach. The spleen is developing in the dorsal mesentery. 

The Abdominal aorta is present in the posterior abdominal wall. In the anterior abdominal wall, the umbilical opening is present. The Diaphragm separates the thorax above and the abdomen below. The central tendon of the diaphragm is derived from the septum transversum. In the gut tube, the anterior esophagus, below which the stomach is present, later continues as the duodenum. It is covered by the double fold of the peritoneum, which encloses the three parts of the gut tube. The ventral mesentery is present in front of the gut tube axis. The dorsal mesentery is present behind the axis of the gut tube. Lesser curvature of the stomach is present in the anterior region. Greater curvature of the stomach is present in the posterior region. Later, the stomach rotates. The liver is developing in the ventral mesentery. The spleen is developing in the dorsal mesentery. The placenta is sending a vein into the liver (left umbilical vein) through the umbilicus. Some parts of the vein will persist, which is known as the adult remnant of the left umbilical vein. The ligamentum teres attaches the liver to the umbilicus. It is carried by the double fold of the peritoneum. It attaches the liver to the anterior abdominal wall and superiorly to the diaphragm. It is called the falciform ligament of the liver, and now it is called the coronary ligament of the liver (anteriorly); it attaches the liver superiorly to the diaphragm.

It carries the (DAV) structure, which is the duct (bile duct), artery (Hepatic artery), and vein (portal vein).

Frequently Asked Questions

Q. The umbilical vein carries

a. Oxygenated blood towards the placenta

b. Deoxygenated blood towards the placenta

c. Oxygenated blood away from the placenta

d. Deoxygenated blood away from the placenta

Answer: Oxygenated blood away from the placenta

Explanation: The left umbilical vein carries blood to the fetus's oxygen supply

Q. Ventral mesogastrium derivatives include all except (JIPMER-2001)

a. Falciform ligament

b. Coronary ligament

c. Lesser omentum

d. Gastrosplenic ligament

Answer: Gastrosplenic ligament

Explanation: Dorsal mesentery forms the Gastrosplenic ligament. The first three ligaments are developed from the septum transversum via the formation of ventral mesentery.

Q. Which of the following structures doesn't develop in the mesentery of the stomach

a. Liver

b. Kidney

c. Spleen

d. Pancreas

Answer: Kidney

Explanation: The kidney and aorta are retroperitoneal

Q. Which one of the following ligaments contains splenic artery (NBEP-2014)

a. Gastrosplenic ligament

b. Splenocolic ligament

c. Splenorenal ligament

d. Splenophrenic ligament

Answer: Splenorenal ligament

Explanation: Gastrosplenic ligament: branch of the splenic artery (short gastric arteries) carries along the greater curvature of the stomach.

Q. Which of the following structures develop in the ventral part of the ventral mesentery of the stomach

a. Falciform ligament

b. Hepatogastric ligament

c. Lesser omentum

d. Splenogastric ligament

Answer: Falciform ligament

Q. Which part of the pancreas does not develop in dorsal mesentery?

Answer: Uncinate process

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