10 GI Embryo

Question 1

What surrounds the endoderm of the embryo

Answer 1

Splanchnic mesoderm

Question 2

The narrowed opening of the yolk sac is

Answer 2

The vitelline duct

Question 3

What is in the foregut

Answer 3

Esophagus
Stomach
Liver
Gallbladder
Pancreas
Upper duodenum

Question 4

What is in the midgut

Answer 4

Lower duodenum
Jejunum
Ileum
Cecum
Appendix
Ascending colon
Proximal 2/3 of transverse colon

Question 5

What is in the hindgut

Answer 5

Distal 1/3 of transverse colon
Descending colon
Sigmoid colon
Rectum
Upper anal canal

Question 6

What does the endoderm make in the GI

Answer 6

Mucosal epithelium (mucosa) and GI glands except for lower 1/3 of anus

Question 7

What does the splanchnic mesoderm make in the GI

Answer 7

Muscular wall (muscularis), vascular elements, CT

Question 8

What does the ectoderm make in the GI

Answer 8

Enteric ganglia, nerves and glia (NCC)

Epithelium of lower 1/3 of anus

Question 9

What are the adult derivatives of the dorsal mesentery

Answer 9

• greater omentum - gastrosplenic, gastrocolic, and splenorenal ligaments
• small intestine mesentery
• mesoappendix
• transverse mesocolon
• sigmoid mesocolon

Question 10

What are the adult derivatives of the ventral mesentery

Answer 10

• lesser omentum - hepatoduodenal and hepatogastric ligaments
• falciform ligament of liver(umbilical V)
• coronary ligament of liver
• triangular ligament of liver

Question 11

What mesentery does the stomach form in

Answer 11

Ventral and it rotates 90 degrees CCW

Question 12

What mesogastrum forms the greater omentum

Answer 12

Dorsal

Question 13

Why does the lesser sac end up behind the stomach

Answer 13

Rotation of stomach

Question 14

Where is the L vagus on the stomach? R?

Answer 14

L - ventral stomach

R - dorsal stomach

Question 15

The ______ surface of the stomach becomes ventral and the ________ surface becomes dorsal

Answer 15

Left; right

Question 16

What causes hypertrophic pyloric stenosis

Answer 16

Inability of the sphincter to relax due to faulty migration of the NCC so ganglion cells of the enteric NS are not properly populated

Question 17

What symptoms are associated with hypertrophic pyloric stenosis

Answer 17

• projectile, non-bilious vomiting after feeding
• fewer and smaller stools
• failure to gain weight

Question 18

What is associated with hypertrophic pyloric stenosis

Answer 18

Increase incidence in infants treated with erythromycin

Question 19

What begins as a diverticulum from gut endoderm

Answer 19

Liver

Question 20

What does the endoderm differentiate into in the liver

Answer 20

Hepatocytes, bile ducts, hepatic ducts

Question 21

What does the splanchnic mesoderm differentiate into in the liver

Answer 21

Stromal, kupffer, and stellate cells

Question 22

What do stellate cells do

Answer 22

Support sinusoidal cells of the liver

Question 23

What functions as the early hematopoiesis organ

Answer 23

Liver

Question 24

What percentage of BW is the liver at week 10? At birth?

Answer 24

10%; 5%

Question 25

Where does the pancreas form

Answer 25

Ventral mesentery

Question 26

What does the dorsal and ventral pancreas form? When does it fuse

Answer 26

D - head, body, tail V - uncinate process 5th month

Question 27

What causes the accessory pancreatic duct

Answer 27

Ventral pancreatic duct that doesn’t disappear

Question 28

What is the prevalence of accessory pancreatic duct

Answer 28

1/3

Question 29

What is a pancreas divisum

Answer 29

Ventral and dorsal pancreatic duct don’t connect internally 4% incidence

Question 30

When is bile formed by hepatic cells

Answer 30

Week 12

Question 31

Bile duct is initially closed but opens via

Answer 31

Recanalization

Question 32

What happens if the bile duct doesn’t recanalize

Answer 32

Biliary atresia

Question 33

What are the extrahepatic or intrahepatic ducts replaced by in biliary atresia

Answer 33

Fibrosis

Question 34

What are the symptoms of biliary atresia

Answer 34

- progressive neonatal jaundice soon after birth - white clay colored stool - dark colored urine - 12-19 month average survival - can be treated with liver transplant

Question 35

When does the spleen form

Answer 35

Week 5 but in week 4 there is a mesenchymal consideration in dorsal mesogastrium

Question 36

What is special about the spleen

Answer 36

It is derived from the mesoderm and not endoderm

Question 37

What does the midgut do during formation

Answer 37

Physiologically herniates at week 6 and back in at week 10

Question 38

How des the ascending and tranverse colon end up anterior

Answer 38

90 degree CCW roatation at 50 days and 180 degree CCW rotation at 70 days

Question 39

What is an omphalocele

Answer 39

Hernitation through umbilicus with peritoneal covering

Question 40

What increases the risk of omphalocele

Answer 40

Trisomy 12 or 18

Question 41

What causes omphalocele

Answer 41

- herniated bowel doesn’t fully retract - lateral body bolding and fusion fails creating a wall weakness - CT of skin and hypaxial mm of body wall does not form normally

Question 42

What is gastroschiscis

Answer 42

Herniation through abdominal wall with no parietal peritoneum covering

Question 43

What is meckel’s diverticulum

Answer 43

Failure of yolk stalk (vitelline duct) connection to the midgut to regress

Question 44

What are the rules of 2 with meckel’s diverticulum

Answer 44

``` 2% incidence 2x more common in males 2% have medical symptoms Usually 2 feet proximal to terminal ileum Usually 2 inches long Usually 2 years of age ```

Question 45

What can meckel’s diverticulum cause

Answer 45

Abdominal swelling, intestinal obstruction, bowel sepsis, GI bleeding

Question 46

What is non-rotation of the midgut loop

Answer 46

Completes first 90 degree rotation but does not do the 180 degree complete rotation

Question 47

What is the consequence of non-rotation of the midgut

Answer 47

Ends up with left-sided colon and right-sided small intestine

Question 48

What is reverse gut rotation

Answer 48

Completes initial 90 CCW but goes 180 CW so the transverse colon ends up posterior to the duodenum

Question 49

What is volvulus

Answer 49

Rolled up or twisted intestines

Question 50

What are the symptoms of volvulus

Answer 50

Acute abdominal pain Vomiting GI bleeding

Question 51

What increases the risk of volvulus

Answer 51

Gut rotation anomalies (non-rotation or reverse rotation)

Question 52

During what month does the lumen of intestines is temporarily obliterated because of endodermal proliferation

Answer 52

5-6th

Question 53

What is duodenal stenosis

Answer 53

Partial occlusion due to ineffective recanalization (usually involves the horizontal and/or ascending parts)

Question 54

What is duodenal atresia

Answer 54

Complete occlusion of lumen

Question 55

What is intestinal stenosis or atresia commonly associated with

Answer 55

Trisomy 21 (Down’s syndrome)

Question 56

The separation of the cloaca forms what

Answer 56

Urethra and anus

Question 57

What allows the distal 1/3 of the anus to be ectodermally derived

Answer 57

Anal plug that is later apoptosed, this is the future pectineal line

Question 58

What is the vascularization of the proximal 2/3 of the anus? Distal 1/3?

Answer 58

IMA; internal iliac A

Question 59

What is the innervation of the proximal 2/3 of anus? Distal 1/3?

Answer 59

Inferior hypogastric N; pudendal N

Question 60

What is the failure of the anal plug to degenerate

Answer 60

Imperforated anus Can be low, intermediate, high, or atresia

Question 61

What is hirschsprung disease

Answer 61

Absence of ganglionic plexus due to absence of migration of NCC

Question 62

What are the symptoms of hirshsprung disease

Answer 62

Increase wall thickenss due to hypertrophy in intestine proximal to aganglionic segment Lack of peristalsis Abnormal colonic dilation or distension

Question 63

What is the treatment of hirschsprung disease

Answer 63

Surgical removal of constricted distal segment