Cell types in the CNS

Question 1

What are the main types of glia in the CNS?

Answer 1

Oligodendrocytes
Microglia 
Astrocytes 
ependymal cells 
oligodendrocyte precursors 
glial stem cells

Question 2

Where in the CNS forms new neurons throughout life?

Answer 2

hippocampus and dentate gyrus

Question 3

How does an H and E stain work?

Answer 3

Haemotoxylin statins nucleic acid blue (nuclelous v blue) and the eosin statins proteins red

Question 4

How does a Luxol fast blue stain work?

Answer 4

Stains myelin blue

Question 5

How does a cressyl violet stain work?

Answer 5

Stains RER violet

Question 6

Are neurons homogenous?

Answer 6

No - large heterogeneity, Purkinje cells have large dendritic tree
UMN are large, excitatory, glutamatergic with long projections and pyramidal cell bodies.
Striatal interneurons are small, spiny, inhibitory GABAergic

Question 7

What is the purpose of oligodendrocytes?

Answer 7

To produce myelin sheath - allow saltatory conduction

Provide metabolic support to the cell - can pass lactate and other supporting substances to the neurons

Question 8

What is the myelin sheath made of?

Answer 8

Multiple layers of the oligodendrocyte membrane wrapped around the axon.

Question 9

Which proteins would you look for to identify myelin? What is unique about them?

Answer 9

MBP, MOG, PLP

most are positively charged whereas the membrane is negatively charged

Question 10

What is the function of microglia?

Answer 10

immune cells
Remove synapses by pruning
phagocytosis - debris/microbes

Question 11

How do microglia vary from other cells in the CNS?

Answer 11

origin is from erythromyeloid progenitors

Question 12

What are the 2 states of microglia?

Answer 12

ramified (resting) and activated

Question 13

Describe the 2 states of microglia

Answer 13

Ramified - processes highly motile, surveying the environment,
Acitvated - activate e.g. by ATP release if cells die, retract processes, move around more, becoming phagocytotic and proliferative

Question 14

How much do astrocytes outnumber neurons by?

Answer 14

10:1

Question 15

What is a common marker for astrocytes?

Answer 15

GFAP

Question 16

What is the difference between fibrous and protoplasmic astrocytes?

Answer 16

fibrous - white matter, less elaborate, contacts with nodes fo ranvier

protoplasmic - grey matter, extremely elaborate, processes contact blood vessels and pial surface

Question 17

What is the function of astrocytes?

Answer 17

development (radial glia)
structural - define brain microarchitecture
homeostatic - buffer K+, glutamate etc.
Buffering of neurotransmitters and also recycling of them into different inactive form
neurovascular coupling - processes bridge neurons and blood vessels, fMRI based on this (measures oxygenated blood flow)

Question 18

Give 3 examples of specialised astrocytes

Answer 18

Bergmann glia - support Purkinje cells metabolically
muller cells - support retina structurally
radial glia - neural stem/progenitor cells

Question 19

What is the BBB made of

Answer 19

endothelial cells, tight junctions
non-fenestrated basement membrane
astrocytes - end feet contact blood vessels and ensheath endothelium
specific transporters for glucose

Question 20

Where lacks the BBB

Answer 20

pineal gland, pituitary, sub fornical organ - anywhere where function is to sense osmolarity and homeostatic regulation

Question 21

What are the ependymal cells

Answer 21

line the ventricles
produce csf - transporters secrete solutes to form osmotic gradient and draw water out of cells
some form of barrier but not as strong as BBB
ciliated

Question 22

What is the choroid plexus?

Answer 22

projections in brain ventricles
made of ependymal cells
villi form around network of capillaries to increase sa
gap junctions form blood-CSF barrier