4.0 Histology of the CNS Flashcards
What defines an ependymal cell as a choroid plexus cell histologically?
Association with pia mater and associated vasculature.
Do ependymal cells have a basal lamina?
Nope.
What are the functions of ependymal cells?
Movement and absorption of CSF .
What are the functions of astrocytes?
- Buffer extracellular K+ levels.
- Guide and physically support movements and locations of differentiating neurons.
- Extend fibrous processes with perivascular feet that cover capillary endothelial cells and form the blood brain barrier. Also helps to move nutrients, wastes, and other metabolites between neurons and capillaries.
- Helps with the removal of neurotransmitters from the microenvironment to help neurons “turn off.”
- Filling tissue defects after CNS injury by proliferation to form an
astrocytic scar
The proximal regions of astrocytes are reinforced by what protein?
Why do we care?
GFAP: Glial Fibrillary Acid Protein
GFAP can be preferentially stained to highlight astrocytes.
What are the six layers of the neocortex?
- Plexiform Layer (molecular layer)
- Small pyramidal cell layer (external granular layer)
- Layer of medium pyramidal cells (external pyramidal cell layer)
- Granular layer (internal granular layer)
- Large pyramidal cell layer (ganglionic layer)
- Polymorphic layer (multiform / polymorphic cell layer)
Where do we find the choroid plexus?
In the roof of the 3rd and 4th ventricles, and in parts of the lateral ventricular walls.
Describe the histological changes associated with Alzheimer’s disease.
The gyri of the cortex thin, and the brain becomes smoother.
β-amyloid plaques and tau (τ) neurofibrillary tangles are identified on sections, as well as neuronal loss.
These plaques interrupt communication between neurons.
Tau proteins form “skeins.”
What cells are responsible for myelination of the CNS?
What embryological layer are these cells derived from?
Oligodendrocytes
Neuroepithelium
What cells are responsible for myelination of the PNS?
What embryological layer do these come from?
Schwann cells
Neural crest cells
What motor proteins are used in anterograde and retrograde transport, respectively?
Anterograde = kinesin.
Retrograde = dynein.
What is the function of microglia in the CNS?
They are the primary defense from microbial invaders.
Originate from monocytes.
What composes the blood - CSF barrier?
Tight junctions between epithelial cells.
What is “neuropil?”
Neuropil: dense network of interwoven nerve fibers &
their branches and synapses, together with glial filaments
What molecules utilize slow transport, and which direction are they headed?
Anterograde only
Tubulin molecules, actin molecules, & neurofilament proteins
What is this tissue?
