Embryo - Development of the neuromuscular system

Question 1

The early neural tube consists of what type of epithelium?

Answer 1

pseudostratified columnar (neuro-) epithelium

Question 2

True or False:

The epithelial cells of the early neural tube are characterized by a high degree of mitotic activity.

Answer 2

True

Question 3

The cellular division and maturation of the epithelial cells in the early neural tube results in:

Answer 3

A population of bipotential progenitor cells, which will give rise to either neuronal or glial progenitor cells

Question 4

Is the marginal layer gray or white matter?

Answer 4

White matter

Question 5

Is the mantle layer gray or white matter?

Answer 5

Gray matter

Question 6

______ neurons and _______ migrate outward to form an intermediate mantle or cortical zone.

Answer 6

Postmitotic neurons and glioblasts

Question 7

_______ processes (myelinated) move out to surround the developing grey matter and form the outer white matter, or marginal zone.

Answer 7

Neuronal

Question 8

List the steps in molecular regulation of nerve differentiation in the spinal cord

Answer 8

1. BMP4&7 secreted in the ectoderm est. a signaling center in the roof plate
2. BMP4 in the roof plate upregulates a cascade of TGF-B proteins, including BMP5&7, activin, & dorsalin
3. SHH from notochord est. additional SHH signaling in the floor plate
4. Overlapping gradient involving the dorsal & ventral factors in est. in the neural tube

Question 9

Paraxial Mesoderm

Answer 9

Longitudinal blocks of tissue on either side of the notochord.
Give rise to the axial skeleton and skeletal muscle

Question 10

Intermediate Mesoderm

Answer 10

Gives rise to the urogenital system and reproductive system

Question 11

Lateral Plate Mesoderm

Answer 11

Gives rise to CT and skeleton of the limbs and smooth muscle and CT of viscera and BVs

Question 12

The Notch Signaling Network

Answer 12

An evolutionarily conserved intercellular signaling pathway that regulates interactions between physically adjacent cells

Question 13

Notch protein _______ in presomitic mesoderm destined for the next somite and then _______ as that somite is established

Answer 13

Accumulates; decreases

Question 14

The ______ in Notch protein activates other segment-patterning genes that establish the somite.

Answer 14

increase

Question 15

Boundaries for each somite are regulated by:

Answer 15

Retinoic acid (RA) and a combination of FGF8 and WNT3a

Question 16

When is RA expressed at high concentrations?

When is RA expressed at low concentrations?

Answer 16

High concentrations - cranially

Low concentrations - caudally

Question 17

When are FGF8 & WNT3a expressed at high concentrations? When are they expressed at low concentrations?

Answer 17

High concentrations - caudally

Low concentrations - cranially

Question 18

The somite divides into three parts:

Answer 18

Sclerotome
Dermatome
Myotome

Question 19

Sclerotome

Answer 19

Ventromedial portion closest to the notocord

Become cartilage; give rise to vertebra

Question 20

Dermatome

Answer 20

Will become the dermis

Question 21

Myotome

Answer 21

Will give rise to muscles

Question 22

Describe the second segmentation, called resegmentation

Answer 22

Takes place only in the sclerotome.

Rostral and caudal halves of somites segregate and refuse with their neighboring halves to form vertebrae

Question 23

Cells of the ______ condense around the notochord and form the vertebrae

Answer 23

Sclerotome

Question 24

What kind of vertebrae a somite becomes is not controlled on a one-to-one basis by the Hox genes, but rather by:

Answer 24

Their interactions

Question 25

MyoD and MYF5

Answer 25

Members of a family of transcription factors called myogenic regulatory factors

Question 26

Somatic Mesoderm

Answer 26

Wall of the body cavity

Question 27

Splanchnic Mesoderm

Answer 27

Visceral, “internal organs”

Question 28

Review the break down of the mesoderm

Answer 28

Slide 47