Embryology of GU and GI Systems

Question 1

What embryological layer forms the gut tube?

Answer 1

The endoderm

Question 2

The _______________ suspends the entire length of the gut from the posterior abdominal wall.

Answer 2

The Dorsal Mesentery

Suspends the entire length of the gut from the posterior abdominal wall

Question 3

What 2 structures arise from the ventral mesentery?

Answer 3

the falciform ligament and lesser omentum

Question 4

Name the 7 Derivatives of the Foregut.

Answer 4

1st and 2nd parts of the duodenum
Esophagus
Liver (Hepatic diverticulum)
Gall bladder (Hepatic diverticulum)
Biliary apparatus (Hepatic diverticulum)
Pancreas
Stomach

Question 5

Name the 6 Derivatives of the Midgut.

Answer 5

Ascending colon
2nd, 3rd, 4th parts of duodenum
Jejunum
Ileum
Cecum with appendix
Proximal 2/3 of Transverse colon

Question 6

Name the 4 Derivatives of the Hindgut.

Answer 6

Distal 1/3 of Transverse colon
Descending colon
Sigmoid colon
Rectum

Question 7

What is the Blood Supply of the Embryological Gut?

Answer 7

Foregut - Celiac trunk
Midgut - superior mesenteric artery (SMA)
Hindgut - inferior mesenteric artery (IMA)

Question 8

Define recanalization in the embryological gut tube.

Answer 8

Opens holes in the embryological gut tube

Question 9

Define stenosis in the embryological gut tube.

Answer 9

Partial recanalization of the gut tube due to an inability to generate a full hole

Question 10

Define atresia in the embryological gut tube.

Answer 10

A failure to recanalize at all; no hole opening in the gut

Question 11

Define Duodenal atresia.

Answer 11

Duodenal atresia – the inability to pass food from the gut tube through to the duodenum because there is no hole

Question 12

What is the Adult Derivative of the LEFT Umbilical Vein?

Answer 12

The left umbilical vein forms the ligamentum teres/round ligament of liver.

Question 13

The stomach rotates ________ or _________on its longitudinal axis

Answer 13

The stomach rotates 90 degrees to the right or clockwise on its longitudinal axis

Question 14

Midgut rotation is a _________ of rotation of ______ degrees around the _____________as its longitudinal axis for rotation.

Answer 14

Midgut rotation is a Counter-clockwise of rotation of 270 degrees around the Superior Mesenteric Artery (SMA) as its longitudinal axis for rotation.

Question 15

What causes Omphalocele?

Answer 15

It results from failure of return of the intestine to the abdominal cavity (covered by peritoneum)

Question 16

What forms from the ventral and dorsal pancreatic buds?

Answer 16

The ventral pancreatic bud becomes most of the head of the pancreas, including the uncinate process

The dorsal pancreatic bud becomes the remainder of the pancreas

Question 17

What forms the annular process of the pancreas?

Answer 17

The annular process is formed by fusion of ventral and dorsal buds all around the 2nd part of the duodenum

Question 18

What are symptoms of an annular pancreas?

Answer 18

A baby will present with vomit that contains bile and complete/partial bowel obstruction

Question 19

Hemorrhoids above the pectinate will be _________ because of ________ innervation.

Answer 19

Hemorrhoids above the pectinate will be painless because of GVA visceral innervation.

Question 20

Hemorrhoids below the pectinate will be _________ because of ________ innervation.

Answer 20

Hemorrhoids below the pectinate will be painful because of GSA somatic innervation.

Question 21

What is Congenital Megacolon (Hirschprung’s) and its cause.

Answer 21

A Congenital Abnormality: s a result of a failure to pass meconium in a full term baby.

Neural crest cells responsible for bowel peristalsis (autonomic innervation) fail to migrate, causing constipation, colonic dilation, and bowel obstruction (no autonomic innervation).

Question 22

What is Meckel’s (ileal) Diverticulum?

Answer 22

A congenital Abnormality due to a remnant of the vitelline duct that causes a syndrome of 2’s:

2 feet from ileocolic IC valve
2 inches long
2% of population
2% symptomatic
2 types of ectopic tissue (gastric and pancreatic)
2 years of age at clinical presentation
2X more common in boys

Question 23

The ______________ becomes the Median umbilical ligament .

Answer 23

The obliterated Urachus becomes the Median umbilical ligament .

Question 24

The ____________ becomes the Medial umbilical folds.

Answer 24

The obliterated umbilical artery becomes the Medial umbilical folds.

Question 25

The ____________ becomes the Medial umbilical folds.

Answer 25

The obliterated umbilical artery becomes the Medial umbilical folds.

Question 26

What forms from the Mesonephric ducts?

Answer 26

Mesonephric ducts - gives the ureteric bud and trigone

Question 27

What forms from the Ureteric bud?

Answer 27

Ureteric bud - ureter, renal pelvis, calices and collecting tubules

Question 28

What is the trigone?

Answer 28

Trigone – triangular shaped area in the bladder connecting the opening of 2 ureters.

Question 29

All the bladder is ____________ except the trigone, kidneys, and ureters, which are ________.

Answer 29

All the bladder is endoderm except the trigone, kidneys, and ureters, which are mesoderm.

Question 30

What causes horseshoe kidney?

Answer 30

The kidneys normally ascend from the pelvis to the retroperitineum and the scrotum descends from the abdomen to the pelvis. Horseshoe kidney is caused by a failure of the kidneys to migrate and they stay in the pelvis, fused at their caudal ends.