CNS Histology Dennis T#2 Flashcards
Describe the typical neruon structure.
Cell body with a large nucleus and nucleolus and nissl bodies. Numerous dendrites extend off of the cell body and one axon from the axon hillock
Describe the presynaptic terminal bouton.
Contains mitochondria and synaptic vvesicles and they release NT via exocytosis
What is a multipolar neuron?
Neuron that has multiple dendrites and one axon with multiple branches, target can be muscle cells or other organs
Bipolar neuron
Centrally positioned ccell body with two processes on each side. One is a dendrite and the other is an axon. Found in the retina
Unipolar neuron?
Found in dorsal root ganglion and dedicated to sensory function. One cell body and one short process that extends and branches into one short and long process. Shorter is positioned centrally within the nervous system and relays info into spinal cord and the longer one goes to target for example skin.
Anoxonic neuron?
Single cell body with multiple dendrites but no axon to communicate through AP just processing information from the dendrites. It is not very common.
What is synaptic communication?
Unidirectional communication that converts an electric signal to a chemical signal via neurotransmitters.
Describe the chemical synapse.
The presynaptic terminal bouton contains mitochondria and synaptic vesicles to be released via exocytosis. They diffuse acorss the cleft to bind on the postsynaptic cell membrane which contains GPCRs or ion channels to cause movement of ions to stimulate or inhibit signal.
What is the electrical synaps
Direct passive flow of electrical currents between neurons through gap junctions. Gap junctions are made of connexon proteins which link the pre and post synaptic membranes. These are found in cardiac muslce.
Far less common in CNS
What is the hallmark marker to identify astrocytes?
Glial fibrillary acid protein GFAP
What do astrocytes do?
Form a network of delicate terminals contacting synapses and other structures. They use perivascular feet to create BBB to block pores on capillary beds.
Choroid plexus structure, location, and function.
Columnar or cboidal cells that line the ventricles and central canal of spinal cord. The apical end has cilia and long microvili that facilitate the movement of CSF and involved in absorption. They do NOT have a basal lamina.
ID
4th ventricle with ependymal cells making up the choroid plexus
ID and function
- MIcroglia- elongated nuclei
- Derived from monocytes
- Immune defense in the CNS
- remove damaged or unactive synapses or cellular debris
ID and function
- Contact multiple axons and wrap axons in myelin.
- Multiple oligodendrocytes can enwrap the same axon.
- Usually small cells with round condensed nuclei and unstained cytoplasm
What are the two types of peripheral glia?
- Neurolemmoytes aka schwann cells:
- myelinate peripheral nerves
- only one cell wraps one segment of an axon
- Satellite cells:
- found in DRG and provides structural and metabolics support for neuronal cell bodies
What are the six layers of the cerebral cortex?
- Molecular: fibers and neuroglial cells
- External granular layer
- External pyrimidal layer
- Inner granular layer
- Ganglionic layer: extra large pyrimidal cells especially in the motor areas
- Multiform polymorphic layer: cells with diverse shapes
Goes youngest to oldest from superficial to deep
What is the most common neurodegenerative disease?
Alzheimer’s Disease
- Amyloid Beta plaques amorphous pink masses in the cortex stained with HE
- Neurofibirillay tangles have accumulation of protein tau, flame shaped skeins formed
What disease is present?
alzheimers
What is the significace of substantia nigra?
- Connections with the cortex, spinal cord, corpus striatum and retiular formation and directly involved in motor function.
- It contains dopamine within the neuromelanin which will inhibit movements
What is being compared?
Brain stem with substantia nigra. Right section has adaquate substantia nigra and the individual on the left is lacking neuromelanin pigment so they had a decrease in dopamine resulting in parkinsons.
What is seen and in what conditions is this seen
Lewy body is seen in the remaining neurons composed of aggregates of alpha synyclein. The halo around the body is hallmark.
Parkinsons disease
Describe the cereballar cortex
Know how to identify histology and what is in each layer
- Molecular: scattered neuronal cell bodies, contains basket cells
- Purkinjie: dendrites extend throughout the moolecular layer, seen in a row speckeled throughout
- Granular: deepest layer of cells and contains small dense packed granular cells and little neurophil. White matter (medulla) is below
What is the dense staining purple?
Granular layer of cereballar cortex containing dense packed neurons and littlel neurophil
outlined section?
Purkinjie layer of the cerebellar cortex
What are the arrows pointing to?
Anterior horns with large motor neuron bodies
ID the dots
