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72 Cards in this Set

  • Front
  • Back
most numerous cells of the CNS
glial cells (estimated to encompass 90% of cells in human CNS)
the term neuroglia means what?
was suggested by who?
suggested by Rudolph virchow in 1859
stain used to visualize glia
Golgi silver stain
achievements of Ramon y Cajal and Pio del Rio-Hortega
used Golgi silver stain to visualize glia

found difft brain regions contain difft types of glial cells
macrogla are derived from what embryologic cell type?
Macroglia include:
ependymal cells
radial glia
axonal ensheathing cells,
primarily found in WHITE MATTER

(can be subdivided into: perineuronal and interfascicular oligodendrocytes)
Perineuronal oligodendrocytes:
found close to neurons in the gray matter
probably don't myelinate
share some ultrastructural features with oligos, but may be new cell type?
Interfacicular oligodendrocytes
myelinate axons to enhance electrical conduction (primarily found in WHITE MATTER)
likely many shapes and many functions, traditionally divided into:
Fibrous astrocytes
Protoplasmic astrocytes
Fibrous astrocytes
primarily in White matter
long fibrillar processes that envelope the NODES OF RANVIER
Protoplasmic Astrocytes
primarily in Gray matter
sheet-like processes that surround synapses
Ependymal cells
-specialized glial cells with cilia
-form a tight columnar type alignment along ventricular and central canal linings
-help circulate CSF
choroid plexus
another type of specialized glial cell
produces CSF
Radial glia
specialized glia that acts as "active" scaffodling in the developing CNS
Microglia are what specialized froms of what cell types?
derived from?
monocyte/macrophage type cells
derived from mesoderm
prenatal migration of microglia
from bone marrow stem cells into all areas of the CNS
prenatal function of microglia
believed to assist in extensive remodeling of fetal CNS by phagocytosing cells that die normally by apoptosis
morphology of microglia in post natal life
small, dense, elongated nuclei, w/o identifiable cytoplasm (special stains show very thing cyto branches radiating from nuclear zone)
microglia territories
individual, non-overlapping
microglia comprise what percentage of CNS cells?
quiescent microglia may be activated by what?
to serve what function?
activated by some brain insult

take on important neuroimmunologic phagocytic functions
Schwann cells are derived from
neural crest cells
Schwann cells can be thought as
glial cells of the PNS
Schwann cells carry out functions in the PNS similar to what cell types of the CNS?
astrocytes, oligodendrocytes and microglia
Functions of Schwann cells:
-ensheathe motor and sensory axons to improve conduction velocities
-important components of the synapse at the NMJ
-have capacity to ingest tissue debris and promote regeneration after injury
glial cells develop after what cells?
neurons within the subventricular zone (SVZ)
during early brain development what accumulates in the SVZ
a dense collection of progenitor cells
2 cell types among the first to mature and leave SVZ
radial glia have long processes that span...
the length of the developing cortex from pia to ventricle
how do neurons get to the cortical plate?
young neurons migrate along processes of radial glia that span length of developing cortex from pia to ventricle
once most of the neurons have left the SVZ what happens?
the remaining progenitor cells within this germinal matrix (of the SVZ) develop into protoplasmic astrocytes or oligodendrocytes
when are neurons born in human embryos?
2nd month
when are astrocytes born in human embryos?
3rd month
oligiodendrocytes are born at what month in human embryonic development?
4th and 5th monghts
when does myelination begin?
during late gestation and continues several years into infancy in a very tract selective manner
which type of glial cell has a greater capcity for turnover?
describe turnever of neurons and oligodendrocytes
post-mitotic cells that persist for life, with LITTLE or NO TURNOVER
describe myelin turnover
does turnover slowly
during development the number of oligodendrocytes is perfectly matched with what?
the number of axons needing to be myelinated
what coordinates the perfect matching of # of oligodendrocytes to # of axons needing to be myelinated?
oligo precursors enter developing white matter and are signalled to divide by peptide mitogens (secreted by astrocytes in areas of active electrical activity)

maturing/electrically fxnal axons- elicit the oligos to populate the area and mature to begin myelination
what prevents oligos from continuing to divide?
they have evolved a molecular counter that tells them to stop dividing after a set # of divisions
like other CNS cells oligos require what in order to survive?
signalling from neighboring cells in the form of trophic growth factors
probably twice as many oligos are produced than are needed during development (as is the case with neurons)
the one's not needed undergo apoptosis
Functions of astrocytes
-structural support and scaffolding (esp. in dvpt)
-tripartite synapse
-regulation of EC [K+]
-induction/maintenace of blood bran barrier and vascular regulation
-produce/secrete trophic factors, neuropeptides, neurotransmitters and other small mols necessary for CNS cell survival and fxn
-produce ECM proteins for neuronal migration
-detox, by sequestering metals etc..
-Ca wave communication
-may ultimately control making/breaking of synapses
general term used to discuss the "inflammatory" response (both acute and chronic) in the brain and spinal cord
primary intrinsic cells of the CNS that can become acutely "activated" to respond to an insult
cells that play an important role in inflammation of the brain
endothelial cells
perivascular cells
circulating lymphoid cells
blood brain barrier
different routes of infection in meningitis and encephalitis
local extension
via PNS
inflammatory process of the leptomeninges and CSF w/in the subarachnoid space
inflammation of the brain parenchyma
either meningitis or encephalitis can be caused by:
INFECTIOUS SPECIES (bacterial, fungal, protozoal, metazoal)
TOXINS (chemical meningitis) or
NEOPLASMS (carinomatous or lymphomatous meningitis)
Cellular responses to CNS infections include:
Reactive Astrocytosis
Microglial Nodules
Circulating Lymphoid Cell Infiltration
Reactive Astrocytosis
aka: gliosis or astrogliosis

acute and/or chronic. astrocytes can enlarge, proliferate, produce abundance of intermediate filaments and extend their processes in an attempt to WALL OFF an area of injury/infection.
bacterial brain abscess consists of:
necrotic tissue, acute inflammatory cells, and organisms
microglial cells which are distributed microglial cells (throughout the CNS and generally quiescent) can respond to the infectious agents by changing shape, moving, secreting cytokines and toxic molecules, and even differentiating into macrophage cells to engulf the organisms
microglial nodules
small collections of microglia that form in the brain parenchyma sometimes around infected neurons.
*most commoney found with viral encelhalitides
Circulating lymphoid cell infiltration
infiltration of lymphocytes, neutrophils, macrophages, and other mononuclear cells, complex signalling involving (APCs of CNS (pervascular&microglia), endothelial cells, and lymphocytes to activate these cells, large multinucleated giant cells (specialized M0s can also form))
Multiple Sclerosis (MS)
autoimmune mediated demyelinating disorder of the CNS

(distinct episodes of neuro deficits, separated in time, attributable to white matter lesions separated in space)

probably a myelin-related protein that has escaped self-tolerance and become an autoimmunogen
pathology of MS is characterized preferential damage of what? and preservation of what?
preferential damage to myelin

relative preservation of axons
factors that influence risk of developing MS:
genetic and environmental
evidence implicates what type of cells as initiating MS
CD4+ Th1 cells (react against myelin Ags and secrete cytokines such as IFN-gamma, activating M0s

demyelination is caused by these activated M0s and their injurious products
gross appearance of MS
irregular shaped white matter plaques throughout the brain and spinal cord in seemingly random locations

acute plaques show abundant lipid-rich MOs and lymphocytes, often cuffing vessels around the edge of the plaque

astrocytes become activated and proliferate in and around the plaque
what two conditions induce pro-inflammatory environment in elderly brain?
impairment of immune function with age (weakened defenses by cells involved in both innate & addaptive immunity)

anti-inflammatory hormones decrease with age
free radical hypothesis of aging suggests what?
that oxidative damage to cell membranes and intracellular proteins increases because of an increase in ROSs and a decrease in the capacity of antioxidant defense mechanisms

increased free radicals can also chronically activate glial cells and promote a pro-inflamm. environment
chronic release of IL-1, IL-6, and TNFa have been show to have what affects in the CNS
pro-inflammatory cytokines

affect neurite outgrowth, synapse plasticity, and neurotransmitter function

can target neuronal CNS fxns to elicit behavioral symptoms of sickness including fever, sleepiness, lethargy and reduced appetite
while most neurodegenerative diseases do not display blood-derived infiltrating mononuclear infiltrates of Autoimmune diseases or infections, they do display:
evidence of cellular neuroinflammation of
Alzheimer's disaese is characterized by loss of what?
characterized by loss of cortical neurons and neuronal function over several years
classic histopathology of Alzheimer's
neurofibrillary tangles
amyloid plaques (whose proteins can illicit glial activation in models, possibly contributing to degeneration and inflammation)
amyotrophic lateral sclerosis
characterized by loss of upper and lower motor neurons in the brain and spinal cord respectively, leading to progressive paralysis and death within several years
what can be measured in the CSF of ALS patients?
proinflammatory cytokines, however not sure if it is a cause or effect of disease
Drugs used to modulate neuroinflammation
NSAIDS (endomethacin, aspirin, ibuprofen)
Antibiotics (minacycline)
Cytokines and cytokine modulatory drugs (IFNs, thalidomide, monoclonal Abs)