T11- Digestive system development Flashcards
When does the primative gut tube form?
During the 4th week with longitudinal and transverse folding
What are intraperitoneal organs
Organs in the peritoneal cavity that are suspended by mesenteries
What are retroperitoneal organs
organs that are positioned between the peritoneum and musculature of the posterior body wall
What is the greater omentum
double layer of peritoneum that drapes inferiorly from the greater curvature of the stomach and proximal duodenum
What is the lesser omentum
A double layer of peritoneum that connects the lesser curvature of the stomach and proximal duodenum to the liver
Dorsal mesentery in embryo
attatches primative gut tube to the dorsal abdominal body wall of the embryo from foregut to hind gut
Ventral mesentery in embryo
attaches only the foregut to the ventral abdominal body wall of the embryo
Derivative of dorsal mesogastrium
greater omentum
Derivatives of ventral mesogastrium
lesser omentum and falciform ligament
Blood supply of the foregut
Celiac trunk
From where and from what does the esophagus develop
from the foregut tube immediatly caudal to the pharynx
Germ cell contributions to the esophagus
Local endoderm: epithelium and glands
Mesenchyme from 4th and 6th pharyngeal arches: skeletal muscle
Local splanchnic mesoderm: smooth muscle
Mechanism by which the esophagus forms
occlusion and recanalization which is completed by the 8th week
Initiation of stomach development
fusiform dialation of the tubular foregut during the 4th week
How does the stomach grow?
ventrodorsally
What does dorsal border of the stomach become
greater curvature of the stomach
How does the ventral border of the stomach rotate
rotates to face the right
How does the dorsal border of the stomach rotate
rotates to face the left
How does the crainial end of the stomach bend
to the left and slightly caudally
How does the caudal end of the stomach bend
to the right and slightly cranially
Where is the stomach (a) suspended from and (b) from what structue is it suspended
from the dorsal abdominal wall by the dorsal mesogastrium
How is the greater omentum formed
during stomach rotation, the dorsal mesogastrium moves to the left and then grows as the grater omentum
What is duodenal stenosis
incomplete recanalization of the lumen
What is duodenal atresia
Failure of the lumen to recanalize
When does the hepatic diverticulum invade the septum transversum
Early in the 4th week
Cranial bud of the hepatic diverticulum forms what
the liver primordium
Caudal bud of the hepatic diverticulum forms what
gallbladder primordium
What does the ventral pancreatic bud become
the uncinate process
Midgut looping
Step 1: herniation of the midgut
elongation of the midgut forms a ventral U-shaped loop that projects into the proximal part of the umbillical cord
When does midgut herniation occur
at the beginning of the sixth week
What is attached to the apex of the midgut loop
the vitelline duct
Cranial limb of midgut loop forms what?
small intestinal loops
Caudal limb of midgut loop forms what?
cecal swelling which is the primordium of the cecum and appendix
Midgut looping
Step 2: rotation of midgut loop
while in the umbillical cord, the loop rotates 90 degrees counterclockwise; this brings the crainal limb (small intestine) to the right and the caudal limb (large intestine) to the left
cranial limb elongates and forms intestinal loops
Midgut looping
Step 3: Retraction of the intestinal loops
intestines return to the abdomen during the 10th week; small intestine returns first and large intestine undergoes a 180 degree counterclockwise rotation as it returns
What is the cloaca
space into which hidgut and allantois (urinary bladder) empty
What happens with growth of the urorectal septum
separation of the cloaca into the urogenital sinus and anorectal canal AND separation of cloacal membrane into urogenital membrane and anal membrane
What is the urogenital sinus
bladder+urethra
What is the anorectal canal
rectum+anal canal
