(5) Cell diversity in developing nervous system Flashcards Preview

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1

what is patterning?

organization of tissues into distinct cell types during development as a result of the unique activities of sets transcription factors and signaling proteins

2

what is a transcription factor

protein that binds to specific DNA sequences

turns gene on/off

DNA--> mRNA--> protein

3

the CNS is patterned along...

its rostral-caudal
anterior-posterior (head to bottom)
dorsal-ventral (back to front)
lateral (sideways) axes

4

signalling factors are expressed either...

ventrally or dorsally

and turn on series of transcription factors that code the developing spinal cord in discrete molecular domains that presage the formation of distinct neural subtypes

5

signalling factors expressed ventrally are..

Sonic Hedgehog (Shh)

6

signalling factors expressed dorsally are...

Bone Morphogenetic Protein (BMP)

Wingless/Int related (WNT)

7

if the genes are misexpressed it can lead to...

cancer

8

cranial nerves are organized along.... & due to...

along anterior-posterior length of the head

due to interactions between the migrating neural crest cells with ectodermal thickenings called placodes

9

how are neural crest cells patterning?

by action of transcription factors called Hox genes

- they are expressed in nested domains along the anterior-posterior axis

10

what are Hox genes

homeotic

11

differentiating neurons accumulate on the..... in region called...

outer layer of the spinal cord in region called marginal zone

12

marginal zone contains ...

post-mitotic (no longer dividing) neurons

13

the inside layer aka.... contains....

aka ventricular zone

contains dividing progenitors

14

what forms adjacent to the spinal cord

dorsal root ganglia

15

dorsal root ganglia are part of .... and contains...

part of peripheral nervous system

contains sensory input from periphery that connects to the developing spinal cord via dorsal root entry zone

16

all dividing cells line....

differentiating neurons move...

dividing cells line central canal of spinal cord

differentiating neurons move outward

17

3 major types of neurons in the spinal cord

IN= interneuron

LMC= lateral motor column, innervates limbs

MMC= medial motor column, innervates axial muscles

18

2 transcription factors involved in embryonic spinal cord

(interneurons an motor neurons)

Pax2

Isl1

19

what does Pax2 label

interneurons

20

what does Isl1 label

motor neurons in ventral horn

- lights up DRG

21

what does the sulcus limitans do?

divides developing neural tube into posterior alar plate and anterior basal plate that will give rise to sensory and motor areas of the spinal cord and brainstem

22

location of alar and basal plate

alar= posterior

basal= anterior

23

Sonic Hedgehog in dorsoventral patterning of the spinal cord

- where is it released from

SHH released from mesoderm and later notochord

signals cells to form the basal plate

24

what does the notochord secrete?

SHH (Sonic Hedgehog)

25

in dorsoventral patterning of the spinal cord what does the ectoderm adjacent to neural plate release?

Bone morphogenetic proteins (BMPs) and Wingless/Int-related (Wnts)

signal cells to form the alar plate

26

what signals cells to form the basal and alar plate

basal= SHH

alar= BMP, Wnt

27

signal molecules are secreted in graded manner in developing neural tube, the concentration is...

higher ventrally (Shh) or dorsally (BMP, Wnt)

28

why are the signalling molecules considered morphogenes

because they are able to pattern tissue in a concentration dependent fashion

29

3 transcription factors involved in dorsoventral patterning of the spinal cord

Pax6 (expressed by somites)

Olig2 (where future motor neurons come from)

FoxA2 (give rise to floor plate)

30

what week marks the beginning of patterning of the spinal cord?

6th week of development

- embryonic spinal cord develops