Feb14 M3-Embryology of the Foregut

Question 1

(IMPORTANT) 2 key events for setting of restricted space for gut formation in order

Answer 1

1. normal umbilical cord size (normal lateral folding of the trilaminar embryo to form cylindrical embryo)
2. normal diaphragm formation

Question 2

liver fct early (6-12 wks)

Answer 2

hemopoietic organ

Question 3

where gut goes 6=12 wks

Answer 3

goes in umb cord, grows there, rotates, comes out

Question 4

where intra embryonic coelum forms

Answer 4

in lateral plate mesoderm

Question 5

what intra embryonic coelum forms (will lead to)

Answer 5

pericardium, pleura, peritoneum

Question 6

origin of the gut wall and origin of body wall

Answer 6

gut wall: splanchnopleure (mesenchyme of the lateral plate ectoderm)
body wall: somatopleure

Question 7

what intra embryonic coelum and midgut connect to

Answer 7

• intra emb coelum to extra emb coelum around yolk sac

- midgut connected to yolk sac

Question 8

(IMPORTANT) yolk sac fct in embryo early embryo + related anomaly

Answer 8

hemopoietic organ + attached to yolk sac. if doesn’t regress = Meckel’s diverticulum

Question 9

2 anomalies in gut tube formation (this being 3rd critical event)

Answer 9

• atresia (bc of problem in the cranial-caudal apoptosis of endodermal cells)
• duplication of the gut

Question 10

rotations that happen in the gut

Answer 10

stomach: clockwise
midgut and hindgut: counterclockwise
+ have to become fixed

Question 11

common gut development problems

Answer 11

malrotation, malfixation apoptosis problem

Question 12

(EXAM) 4 things in order for normal gut embryogenesis

Answer 12

1. embryo folding and umb cord formation
2. diaphragm formation
3. normal gut rotation and fixation
4. normal gut apoptosis

Question 13

(EXAM) consequence of defective embryo folding and umb cord formation

Answer 13

umbilical herniations

Question 14

(EXAM) consequence of defective diaphragm formation

Answer 14

diaphragmatic herniation

Question 15

(EXAM) consequence of defective gut rotation and fixation

Answer 15

malrotation of the gut

Question 16

(IMPORTANT) function of dorsal mesentery for gut dev + other name for it

Answer 16

carries veins, arteries, lymphatics and nerves. (is the visceral peritoneum)

Question 17

what’s inside the visceral peritoneum

Answer 17

visceral epithelium (came from splanchnopleure)

Question 18

kidneys and gonads intra or retroperitoneal

Answer 18

retroperitoneal

kidneys = primarily retroperitoneal

Question 19

(IMPORTANT) space that can form behind ascending and descending colon if incomplete fixation + consequence

Answer 19

paracolic gutters. can be sites of herniation

Question 20

secondarily retroperitoneal structures

Answer 20

D2,D3,D4. ascending and descending colon and mesocolon

Question 21

vessels in primitive mesentery and their origin

Answer 21

celiac trunk, SMA, IMA (come from aorta feeding vessels in dorsal mesentery)

Question 22

name of lymph nodes draining the foregut

Answer 22

celiac nodes

Question 23

midgut is from where to where

Answer 23

from duodenum (at common bile duct, so foregut goes til there) to two thirds of transverse colon

Question 24

region where spleen forms

Answer 24

mesogastrium

Question 25

other structures forming in mesogastrium

Answer 25

gastrosplenic ligament and lienorenal ligament

Question 26

dorsal pancreatic bud origin and what duct is in there

Answer 26

duodenum endoderm. has the dorsal pancreatic duct

Question 27

2 supporting structures for gut rotation and holding it in umbilical cord

Answer 27

superior and inferior retention bands

Question 28

(IMPORTANT) superior retention band becomes what

Answer 28

ligament of Treitz

Question 29

(IMPORTANT) inferior retention band becomes what

Answer 29

phrenicocolic ligament

Question 30

spleen fct in embryo (2)

Answer 30

1. hemopoietic organ

2. separates the 2 lig near it from the omental bursa (a fluid filled sac lined by mesothelium)

Question 31

hemopoietic organs transition in order

Answer 31

1. yolk sac
2. liver
3. spleen

Question 32

(IMPORTANT) why dorsal pancreatic duct continuous from duodenum to spleen

Answer 32

mesogastrium and mesoduodenum are continuous

Question 33

spleen formation anomaly

Answer 33

can get a 2nd accessory spleen in the pancreatic tail (bc spleen formed in mesogastrium)

Question 34

cells that are precursors of hemopoietic organs like the spleen

Answer 34

hemangioblasts (hemopoietic stem: forms all blood cell lineages. angioblasts: form endothelium)

Question 35

ventral mesentery only associated (found) where

Answer 35

with foregut structures (where hepatic duct forms and around liver)

Question 36

liver forms where

Answer 36

in mesenchyme called septum transversum

Question 37

anomaly possible in mesenteric arteries

Answer 37

celiac trunk and SMA can be joined (bc initially all vessels go to yolk sac but then separate in 3 groups)

Question 38

2 very important structures for midgut rotation and duodenum fixation

Answer 38

ligament of Treitz (and other important structure is phrenicocolic ligament)

Question 39

consequence of lig of Treitz too long

Answer 39

U shaped duodenum

Question 40

other importance of lig of Treitz

Answer 40

needed to make duodenum retroperitoneal (push it on the wall)

Question 41

phrenicocolic ligament attaches where

Answer 41

diaphragm to splenic flexure of the colon