Lecture 10

Question 1

What are the three zones of the mesoderm?

Answer 1

paraxial mesoderm
intermediate mesoderm
lateral plate mesoderm

Question 2

Describe the paraxial mesoderm

Answer 2

thick column of mesoderm closest to and parallel with the notochord

Question 3

What zone of the mesoderm becomes segmented into somites?

Answer 3

paraxial

Question 4

What zone of the mesoderm becomes the urogenital system?

Answer 4

intermediate

Question 5

What zone of the mesoderm splits to form lining of body cavities and mesoderm of most internal organs as well as limbs?

Answer 5

lateral plate

Question 6

Describe the intermediate mesoderm

Answer 6

narrow column of mesoderm

Question 7

Describe the lateral plate mesoderm

Answer 7

thin plate of mesoderm lateral to intermediate mesoderm

Question 8

________ are initial pairs of segments of mesenchyme that begin to develop along and on either side of the neural plate in the paraxial mesoderm

Answer 8

somitomeres

Question 9

New somitomeres are added ______ as the primitive streak regresses

Answer 9

caudally

Question 10

_______ are more dense, bocks of mesoderm that form along the notochord

Answer 10

somites

Question 11

In a ______ direction, a pair of somitomeresis are transformed into a pari of somites every few hours

Answer 11

caudal

Question 12

What is the wavefront mechanism in somite differentiation?

Answer 12

increase in FGF-8–mitosis in mesenchymal cells in posterior primitive streak
increase in retinoic acid more anteriorly opposes action of FGF-8

Question 13

What is the segmentation clock in somite differentiation?

Answer 13

oscillating expression of molecules in notch pathway that is expressed along a time line (90 min/ somite in chick embryo)

Question 14

In the segmentation clock, ______ will become concentrated at the future anterior border of a somite and _____ will become concentrated at the future posterior border of a somite

Answer 14

lunatic fringe, c-hairy

Question 15

In the segmentation clock, cells at the anterior border of the somite express _____ and cells of the posterior border of the anterior somite will express ____ resulting in a tissue between the two adjacent somites

Answer 15

Eph A (receptor)
Eph B  (ligand)

Question 16

What is the dermomyotome?

Answer 16

dorsal lateral part of a somite

Question 17

_____ signaling from the notochord and ____ signaling from the dorsal neural tube create a balance that causes the myotome portion to commit to the myogenic lineage

Answer 17

Shh, Wnt

Question 18

______ inhibits _____, which would normally inhibit myogenesis

Answer 18

Noggin; BMP-4

Question 19

What does BMP-4 produced by the lateral plate do?

Answer 19

suppresses myogensis in the ventrolateral dermomyotome and stimulates cells from this area to migrate from the somite into the limb bud

Question 20

_____ from the myotome signals the sclerotome to produce _____, which causes the anterior and posterior borders of the each somite to form the syndetome which is the precursors of tendons

Answer 20

FGF, scleraxis

Question 21

What does the sclerotomal portion fo each somite do?

Answer 21

breaks up into an anterior and posterior portion to create gaps that allow nerves to grow out form the neural tube into the epaxial segmental musculature derives from the myotomes

Question 22

The future intermediate mesoderm responds to ___ and ___ and becomes intermediate mesoderm that expresses ____

Answer 22

BMP, activin, Pax-2

Question 23

What is the intermediate mesoderm associated with forming?

Answer 23

pronephros, and later the mesonephros

Question 24

Cranial and caudal extent of the intermediate mesoderm is dependent on expression of ____ and ____

Answer 24

Hox-4 and Hox-11

Question 25

Early heart forming cells arise from where?

Answer 25

epiblast

Question 26

In early heart forming cells, the cells migrating through the anterior primitive streak form the ______

Answer 26

outflow track

Question 27

In early heart forming cells, the cells migrating through the middle primitive streak form the ______

Answer 27

ventricles

Question 28

In early heart forming cells, the cells migrating through the posterior primitive streak form the ______

Answer 28

atria

Question 29

What are the cardiac tubes?

Answer 29

bilaterally paired tubes that form from the cariogenic mesoderm and fuse beneath foregut to form single tube

Question 30

What does the outer layer of the cardiac tubes form?

inner layer?

Answer 30

outer: myocardium
inner: endocardium

Question 31

What is important in wavefront moment and is expressed because of the specific balance between FGF-8 and retinoic acid concentrations?

Answer 31

Mesp-2

Question 32

the cardiogenic plate arises from ______

Answer 32

splanchnic mesoderm