Endoderm

Question 1

Markers of pluripotency in epiblast

Answer 1

Nanog/Oct4

Question 2

Primitive endoderm markers in hypoblast

Answer 2

Gata6/Sox17

Question 3

Embryonic Origin of the Endoderm: Sea urchin

Answer 3

Ectoderm
Endoderm
Mesoderm

Question 4

Embryonic Origin of the Endoderm: Xenopus

Answer 4

Ectoderm
Mesoderm
Endoderm

Question 5

Embryonic Origin of the Endoderm: Zebrafish

Answer 5

Ectoderm
Mesoderm
Mesendoderm
Yolk

Question 6

Embryonic Origin of the Endoderm: Mouse

Answer 6

Shaped like a cap
Ectoderm outside
Mesoderm and endoderm goes inside

Question 7

Mesendoderm becomes endoderm in presence of HNF

Mesendoderm becomes mesoderm in the presence of Nkx^2.5

Answer 7

Evolution: Diploblastic to triploblastic bilateria

Question 8

Major Functions of the Definitive Endoderm

Answer 8

INDUCE formation of mesoderm/mesodermal organs

CONSTRUCT linings of digestive and respiratory tubes

Question 9

Endoderm-Mesoderm Interaction

Answer 9

1. Shh in endo
2. Reception of Shh protein in meso
3. Hox gene expression in meso
4. Specification of meso
5. BMPs, FGFs made by meso
6. Reception of paracrine signals by endo
7. Specification and differentiation of endo
8. Paracrine factors
9. Differentiation of meso

Question 10

Stages of endoderm development

Answer 10

1. Endoderm formation
2. Tube formation
3. Bud formation
4. Organ-specific cyto-differentiation

Question 11

Regional expression of TFs in endoderm

In the chick, it appears to be regionally specified even before it forms the tube

Question 12

Timeline of endoderm organ formation in mouse

Answer 12

E7.5 (Endoderm formation)
- Gastrulation
- Mesendoderm and ectoderm
- Mesoderm and endoderm

E8.5 (Endoderm patterning)
- Endoderm becomes foregut, midgut, and hindgut

(Organ specification)

E9.5 (Organ buds)

(Proliferation differentiation)

Question 13

Patterning of the gut tube

Answer 13

Anterior part - Liver
Median part - Dorsal pancreas
Posterior part - Hindgut

Question 14

TFs in the early gut tube

Answer 14

Foregut
- TTF1/Nkx2.1
- Nkx2.6
- Pax8
- Pax9
- Hex1
- Hoxb1

Fore/midgut
- Pdx1
- Pax4
- Pax6
- Nkx2.2
- Isl-1
- NeuroD

Mid/hindgut
- cdx2
- Hoxd genes

Question 15

Which transcription factor regulates patterning of intestinal epithelium

Answer 15

Cdx2

Question 16

Derivatives of the Endoderm

Answer 16

Digestive tube, (esophagus, stomach, intestine) liver, pancreas and, gall bladder

Respiratory tube, pharynx (tonsils, thyroid, thymus, and parathyroid) trachea bronchi, lungs

Question 17

Derivatives of the foregut

Answer 17

1. Pharynx and its derivatives
2. The lower respiratory tract
3. The esophagus
4. The stomach
5. The duodenum, proximal to the ampulla of Vater
6. The liver
7. The pancreas
8. The biliary apparatus

Question 18

Derivatives of the midgut

Answer 18

1. the small intestine (except for the proximal duodenum)
2. the cecum
3. the appendix
4. the ascending colon
5. the right 1/2 to 2/3 of the proximal part of the transverse colon

Question 19

Derivatives of the hindgut

Answer 19

1. cloaca
2. urogenital sinus
3. urinary bladder

Question 20

GERM LAYER ORIGIN OF GI TRACT

Endoderm: source of the epithelial lining of the gastrointestinal tract, liver, gallbladder, pancreas.

Mesoderm: connective tissue, including the wall of the gut tube and the smooth muscle

Ectoderm: NCC is the source of the PNS, including the neurons of the GI tract (enteric nervous system)

Question 21

an area where your common bile duct meets your pancreatic duct.

Answer 21

Ampulla of Vater