spinal cord formation

Question 1

The Hox genes in the spinal cord formation occurs in what positional pattern?

Answer 1

dorsal-ventral pattern

Question 2

During formation of the spinal cord, the arrangement of certain groups of motor neurons is in what pattern?

Answer 2

anterior-posterior pattern

Question 3

The lateral motor neuron columns supplying the limbs are only present at what limb levels?

Answer 3

forelimb and hindlimb levels

Question 4

The column supplying the axial muscle extends from which to which region of the spinal cord?

Answer 4

cervical to beginning of lumbar region.

Question 5

The neural tube is formed in what pattern?

Answer 5

Dorsal-ventral pattern (from back to front)

Question 6

What cells are composed of in the floor plate?

Answer 6

columnar cells

Question 7

In the floor plate cells, the medial columns supply what structure of the body?

Answer 7

the axial and and body wall muscles

Question 8

In the floor plate cells, the lateral columns supply what structure of the body?

Answer 8

limbs muscles

Question 9

The dorsal midline of the spinal cord is called the?

Answer 9

roof plate

Question 10

The dorsal-ventral patterning of the spinal cord is made possible by initially receiving signals from where and later from where?

Answer 10

nearby tissues; later from the floor plate and roof plate

Question 11

The notochord induces which plate, roof or floor?

Answer 11

floor plate

Question 12

At low concentrations of signals sending from the notochord, what structure do they form?

Answer 12

motor neurons

Question 13

Notochord signal concentrations can be shown by grafting experiments. Briefly state the experiment

Answer 13

the notochord is grafted adjacent to different dorsal-ventral levels of the neural tube. An ectopic floor plate will form in close proximity and motorneurons a bit further away.

Question 14

State the inducing signal expressed by the notochord.

Answer 14

sonic hedgehog (SHH)

Question 15

Why is the inducing signal thought to be shh?

Answer 15

1. shh is expressed in the notochord
2. Shh will induced floor plate and motor neurons when applied to the neural tube.
3. the floor plate and motor neurons do not form when knockout in mouse

Question 16

Mapping studies in the chick has shown that in normal development of which part of the floor plate is directly derived from what node? And the lateral parts are induced from where?

Answer 16

the medial part of the floor plate is directly derived from Hensen’s node and the lateral parts are induced from the surrounding neuroepithelium.

Question 17

Does the floor plate itself make shh?

Answer 17

Yes

Question 18

The floor plate does not take over the signaling function of the notochord. True or false?

Answer 18

False; the floor plate takes over when it is formed and expresses shh.

Question 19

Shh represses some transcription factor genes such as?

Answer 19

pax3 and pax7

Question 20

The transcription factor genes are initially expressed all over the neural tube. But become repressed by the signal in which direction?

Answer 20

ventral

Question 21

Misexpression of the transcription factors will result in mix-formation of the ventral cell types. True of false?

Answer 21

True

Question 22

Later transcriptional factors are expressed in the neural tube at each dorsal ventral level; they are necessary for the formation of what?

Answer 22

motor neurons and oligodendrocytes

Question 23

What induces the roof plate?

Answer 23

BMP from the epidermis

Question 24

The signals from the two centers, roof plate and floor plate, induce what kind of expression of the pax genes that brings out what pattern?

Answer 24

nested expression of the pax genes; brings out neuronal differentiation pattern

Question 25

The dorsal midline of the neural tube arises from the which part of the neural plate margin?

Answer 25

lateral margin of the neural plate where it contacts the epidermis

Question 26

The epidermis expresses BMP4 and BMP7; what do these BMPs do to the pax transcription factor genes?

Answer 26

They elevate the expression of pax3 and pax 7 when applied to the neural plate.

Question 27

The central nervous system and the peripheral nervous system are derived from which germ layer?

Answer 27

ectoderm

Question 28

Define neurulation:

Answer 28

How the ectoderm begins to give rise to the neural system

Question 29

Dorsal cell types such as the sensory relay neurons are derived from the roof plate signals. What signals are involved?

Answer 29

bmp4, bmp7 and dorsalin (TGF-beta)

Question 30

It is thought that the overall dorso-ventral patterning arises from the combined effects of the gradients of Shh from the floor plate and BMPs from the roof plate and dorsalin from the roof plate. True of false?

Answer 30

True

Question 31

The ectoderm is derived into three major parts of the developmental system. What are they?

Answer 31

Neural tube, neural crest, outer ectoderm(mainly the epidermis)

Question 32

State three key events that happen during neurulation”

Answer 32

1. attachment of notochord to floor plate
2. folding of neural tube. Delamination of neural crest cells
3. neural tube closure, notochord detaches from floor plate, crest migration, roof plate formed

Question 33

The adult spinal cord is in laminal organization of which, grey or white matter?

Answer 33

grey

Question 34

How many layers in the spinal cord has been divided into by Rexes?

Answer 34

9

Question 35

The white matter contains what fibers connect the brain and the spinal cord?

Answer 35

ascending and descending fibers

Question 36

What level of ability to differentiate is the ectoderm at?

Answer 36

pluripotent level

Question 37

un-differentiated ectodermal cells are called?

Answer 37

progenitor or precursor cells

Question 38

What can totipotent cells give rise to?

Answer 38

embryonic and extraembryonic tissues

Question 39

What is a morphogen?

Answer 39

protein that provides positional information to cells via a concentration gradient and alter cell fates

Question 40

What is induction?

Answer 40

Instructing the development of cells through local communication among the embryonic cells

Question 41

During development groups of cells called what secrete inducing signals?

Answer 41

organizing centers

Question 42

Lewis Wolpert coined the term “positional information” to determine what characteristic?

Answer 42

The French flag problem; The transplanted cells retain their identities (knowledge of which flag they belong to) but also respect the positional effects of the host (ie their position within the other flag).