Embryology of the Peritoneum

Questions and Answers

What is the role of the dorsal mesentery during embryonic development?

It is responsible for the development of retroperitoneal organs.

It connects intraperitoneal organs to the abdominal wall.

It provides a double layer membrane from the esophagus to the rectum. (correct)

It forms the cloaca from the allantois.

Which of the following correctly describes retroperitoneal organs?

They are completely encased by the parietal peritoneum.

They develop from the endoderm.

They are suspended by the dorsal mesentery.

They are covered by peritoneum only on their anterior surface. (correct)

Which embryonic structure contributes to the formation of the umbilical cord?

Connecting stalk (correct)

Dorsal mesentery

Cloaca

Yolk sac

What type of mesodermal tissue contributes to the development of the foregut, midgut, and hindgut?

Splanchnic mesoderm Signup and view all the answers

What defines the primitive dorsal and ventral mesenteries?

They form from the fusion of mesodermal layers. Signup and view all the answers

What is the origin of the stomodeum in the gastrointestinal tract?

Ectoderm Signup and view all the answers

Which description best fits intraperitoneal organs?

They are completely surrounded by peritoneum and connected to the body wall. Signup and view all the answers

What is the anatomical location of the proctodeum in the gastrointestinal system?

Caudal end of the GI tract. Signup and view all the answers

What is the primary reason for the faster growth of the dorsal wall of the stomach compared to the ventral wall?

Proliferation of dorsal mesoderm Signup and view all the answers

Which structure connects the spleen to the posterior body wall in the region of the left kidney?

Lienorenal reflection Signup and view all the answers

At the end of the fifth week, what notable positional change occurs with the spleen and pancreas?

Both organs are positioned in the dorsal mesogastrium Signup and view all the answers

What anatomical structure is formed as a result of the stomach's rotation around its anteroposterior axis?

Omental bursa Signup and view all the answers

What is the significance of the gastrolienal reflection?

Connects the spleen to the stomach Signup and view all the answers

Which transcription factors are primarily involved in the differentiation of liver and biliary cell lineages?

HNF3 and HNF4 Signup and view all the answers

What is the role of Bone Morphogenetic Proteins (BMPs) in the development of prospective liver endoderm?

They enhance the competence to respond to FGF2. Signup and view all the answers

During which month of gestation does insulin secretion begin?

5 months Signup and view all the answers

What specific cells are produced from the expression of both PAX4 and PAX6?

Insulin and somatostatin cells Signup and view all the answers

From which type of tissue does the Islet of Langerhans develop?

Parenchymatous tissue Signup and view all the answers

The dorsal pancreatic bud is located in which part of the anatomy?

In the dorsal mesentery Signup and view all the answers

Which of the following cells does not arise from the expression of PAX6 alone?

Insulin cells Signup and view all the answers

What is the anatomical relationship between the ventral pancreatic bud and the bile duct?

The ventral bud is adjacent to the bile duct. Signup and view all the answers

What significant change occurs to the cloacal membrane during development?

It ruptures to form the anal opening. Signup and view all the answers

What is the total degree of rotation that the intestinal loops undergo during herniation and return?

270 degrees. Signup and view all the answers

Which of the following statements correctly describes the development of the hindgut?

The terminal hindgut enters the urogenital sinus. Signup and view all the answers

At what point does the epithelium of the anal canal transition from columnar to stratified squamous?

After the cloacal membrane ruptures. Signup and view all the answers

What mesodermal structure separates the allantois and hindgut during development?

Urorectal septum. Signup and view all the answers

What is the primary function of mesenteries in the body?

Provide pathways for vessels, nerves, and lymphatics Signup and view all the answers

Which cells are responsible for forming the enteric nervous system?

Neural crest cells Signup and view all the answers

During embryonic development, at what day is the umbilical cord typically formed?

Day 35 Signup and view all the answers

How do the midgut rotations occur as it retracts into the abdomen?

Rotate 90 degrees counterclockwise Signup and view all the answers

What causes fetal duodenal obstructions, except for which option?

NOTA Signup and view all the answers

Study Notes

Peritoneum and Mesenteries

The parietal peritoneum narrows by the 5th week of embryonic development.
Dorsal mesentery arises from the fusion of mesodermal layers, extending from the esophagus to the rectum.
Intraperitoneal organs are fully enveloped by double layers of peritoneum; retroperitoneal organs lie against the posterior body wall and have peritoneum only on their anterior surfaces.

Primitive Gut Development

The primitive gut is divided into stomodeum (cranial end), foregut, midgut, hindgut, and proctodeum (caudal end).
The foregut, midgut, and hindgut originate from splanchnic mesoderm.
The ectoderm forms the anal pit in the proctodeum.

Pancreas Development

The pancreas originates from two buds (ventral and dorsal), with differentiation occurring during the 3rd month of gestation.
Hormones are secreted by distinct cell types: β cells produce insulin, α cells produce glucagon, δ cells produce somatostatin, and 𝛾 cells produce pancreatic polypeptide.
Pancreatic development is regulated by specific transcription factors, including PAX4 and PAX6.

Spleen Development

Developed from the proliferation of mesoderm in the dorsal mesogastrium.
Connected to the posterior body wall by the lienorenal reflection and to the stomach by the gastrolienal reflection.

Organ Rotation and Gut Lengthening

The stomach undergoes rotations, which alter the positions of the pylorus and cardia.
The small intestine continues to elongate while coiling occurs.
The large intestine lengthens significantly but does not coil like the small intestine.

Urogenital and Cloacal Development

The hindgut contributes to the formation of the bladder and urethra.
The urorectal septum separates the allantois from the hindgut, with the cloacal membrane delineating the ectoderm from endoderm.
Rupture of the cloacal membrane at the 7th week marks the formation of the anal opening.

Molecular Regulation

Bone Morphogenetic Proteins (BMPs) from the septum transversum enhance liver endoderm differentiation via FGF2.
Hepatocyte nuclear transcription factors are critical in regulating hepatocyte and biliary cell linage differentiation.

Key Genes

HOX genes, particularly PDX1 and CDx1, are implicated in gut tube patterning and development.

Study Questions Overview

Key periods for umbilical cord formation: occurs by day 35.
Regions of the primitive gut: foregut, midgut, hindgut.
Mesenteries serve as pathways for vessels, nerves, and lymphatics.
Enteric nervous system cells originate from neural crest cells.
Fetal duodenal obstructions are linked to various developmental abnormalities.
Interstitial cells of Cajal function as pacemakers within the gastrointestinal tract.
Midgut rotation during retraction into the abdomen occurs counterclockwise by 90 degrees.

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Description

Explore the development of the parietal peritoneum and its reflections during the fifth week of embryonic growth. This quiz covers concepts such as the dorsal mesentery formation and the significance of tail folding in relation to the allantois.