Gut Rotation Flashcards
What 3 germ layers are made due to cranial-caudal folding?
Mesoderm, Ectoderm, Endoderm.
Developmentally, what separates the abdominal cavity?
Septum transversum and pleuroperitoneal membrane.
From what type of mesoderm does the parietal layer of peritoneum arise?
Somatic mesoderm.
From what type of mesoderm does the visceral layer of peritoneum arise?
Splanchnic mesoderm.
How many layers and between which structures, are the peritoneal layers of the mesentery and omentum?
Mesentery: 2 peritoneal layers between organ and body wall
Omentum: 2 peritoneal layers between 2 organs
What organs make up the foregut?
Stomach, duodenum, liver, gallbladder, pancreas.
What organs make up the midgut?
Jejunum, ileum, cecum, appendix, ascending colon, first 2/3 transverse colon
What organs make up the hindgut?
Last 11/3 transverse colon, descending colon, sigmoid colon, rectum
Which organ is primary retroperitoneal?
Rectum.
Which organs are secondary retropertioneal?
Duodenum, pancreas, ascending colon, and descending colon
What role does Wnt-5a and Hox expression play in the primitive devlopment of the foregut and hindgut?
Initially, the gut tube is supposed to be the hindgut due to Wnt-5a signaling. But, Wnt antagonists repress hindgut identity in the cranial section of the gut tube. Transcription factors (Hhex, Sox2, Foxa2) then allow it to have a foregut identity. Cdx2 and Pdx1 cause Hox expression in the midgut –> hindgut and this makes the divisions of the small and large intestine and sphincters at the junctions
How is the lesser sac/omental bursa formed?
This occurs through rotation of the stomach. Barx1 gene causes dilation of the dorsal part of the foregut –> 90 degree rotation with duodenum = rotation of dorsal mesogastrium (lesser omentum) that is attached to liver == lesser sac/omental bursa behind stomach. Lesser omentum connects liver to stomach and liver is pulled to right side.
What is congenital pyloric stenosis?
This is hypertrophy of the pyloric sphincter which causes food to get backed up into the stomach and causes vomiting.
How is the liver developed?
hepatic/liver bud off foregut into –> septum transversum –pushed of –> peritoneum. Part not totally pushed out = bare area. Ventral mesentery = falciform ligament that connects liver to anterior abdominal wall. Hepatoduodenal ligament connects liver to duodenum and contains the portal triad.
How is the gallbladder formed?
Liver bud –> Cystic diverticulum –> gallbladder