Cell types in the CNS Flashcards
What are the main types of glia in the CNS?
Oligodendrocytes Microglia Astrocytes ependymal cells oligodendrocyte precursors glial stem cells
Where in the CNS forms new neurons throughout life?
hippocampus and dentate gyrus
How does an H and E stain work?
Haemotoxylin statins nucleic acid blue (nuclelous v blue) and the eosin statins proteins red
How does a Luxol fast blue stain work?
Stains myelin blue
How does a cressyl violet stain work?
Stains RER violet
Are neurons homogenous?
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
What is the purpose of oligodendrocytes?
To produce myelin sheath - allow saltatory conduction
Provide metabolic support to the cell - can pass lactate and other supporting substances to the neurons
What is the myelin sheath made of?
Multiple layers of the oligodendrocyte membrane wrapped around the axon.
Which proteins would you look for to identify myelin? What is unique about them?
MBP, MOG, PLP
most are positively charged whereas the membrane is negatively charged
What is the function of microglia?
immune cells
Remove synapses by pruning
phagocytosis - debris/microbes
How do microglia vary from other cells in the CNS?
origin is from erythromyeloid progenitors
What are the 2 states of microglia?
ramified (resting) and activated
Describe the 2 states of microglia
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
How much do astrocytes outnumber neurons by?
10:1
What is a common marker for astrocytes?
GFAP
What is the difference between fibrous and protoplasmic astrocytes?
fibrous - white matter, less elaborate, contacts with nodes fo ranvier
protoplasmic - grey matter, extremely elaborate, processes contact blood vessels and pial surface
What is the function of astrocytes?
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)
Give 3 examples of specialised astrocytes
Bergmann glia - support Purkinje cells metabolically
muller cells - support retina structurally
radial glia - neural stem/progenitor cells
What is the BBB made of
endothelial cells, tight junctions
non-fenestrated basement membrane
astrocytes - end feet contact blood vessels and ensheath endothelium
specific transporters for glucose
Where lacks the BBB
pineal gland, pituitary, sub fornical organ - anywhere where function is to sense osmolarity and homeostatic regulation
What are the ependymal cells
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
What is the choroid plexus?
projections in brain ventricles
made of ependymal cells
villi form around network of capillaries to increase sa
gap junctions form blood-CSF barrier
