04. Neurohistology (Dennis) 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?
production of CSF
arachnoid villi reabsorb
What are the functions of astrocytes?
- BBB
- Reuptake NTMs
- Regulate Ion Concentration
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)
What are the three layers of the hippocampus?
What are the three layers of the dentate gyrus?
What is contained within each of these layers?
Hippocampus
- Polymorphic layer
- Nerve fibers and small cell bodies of interneurons
- Middle pyramidal layer
- Hippocampal pyramidal cells
- Molecular layer
- Dendrites of the pyramidal cells
Dentate Gyrus
- Polymorphic layer
- Nerve fibers and cell bodies of interneurons
- Middle granular layer
- Round neuronal cell bodies of dentate granule cells
- Molecular layer
- Dendrites of granule cells
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
- promiscuous-like to touch many axons, single axon wrapped by many oligo.
- appear as small cells, rounded, condensed, unstained cytoplasm
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 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 the function of the choroid plexus?
Modified ependymal cells release CSF.
What is this tissue?
molecular layer-neuropil and neuronal cell bodies
purkinje cells-extend dendrites throughout the molecular layer as branching nerve fibers
granular layer-contians various small neurons (granules) and little neuropil
organized into folia with the cerebellar medulla located deep
Where do we find bipolar neurons?
Sensory neurons of the retina, olfactory mucosa,
and inner ear
Where do we find unipolar / pseudounipolar neurons?
“Other” sensory neurons, including
the dorsal root ganglia & cranial ganglia
What do we call the grainy substance found in a neuron?
Nissl substance / bodies.
Slow Transport
Vs.
Fast Transport
anterograde-cytoskeletal elements
bidirectional-retrograde movement of toxins/viruses (shingles)
Axonal synapses
Not always axon to dendrite
can be axon to soma or axon to axon
allows modulation of signals
Electrical Synapse
Uses gap junctions
links pre- and post-synaptic membranes
contains connexon proteins
found in retina, olfactory, and inf. olivary nucleus
