The document summarizes the histology of neurons and the nervous system. It describes the key parts of neurons including the cell body, axon, and dendrites. It then discusses the different types of neuroglial cells that provide support to neurons in the central and peripheral nervous systems. Finally, it briefly outlines the histological structure and layers of the cerebellar cortex.

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3. Histology of Neuron
 Principle cells of Nervous Tissue
 Consist of 3 parts :
 CELL BODY (perikaryon/soma)
 A single AXON
 Multiple DENDRITES
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4. CELL BODY (PERIKARYON)
• Central portion of the cell
• Generally are polygonal
• Different shape and size  characteristic regions of nervous system
• Contain : Nucleus and Perinuclear cytoplasm
 Nucleus :
• large, spherical to ovoid and centraly located
• a single prominent nucleolus
• finely dispersed chromatin
 Cytoplasm : contains :
• R.E.R and S.E.R.
• Polyribosomes
• Basic dyes (a+b) Nissl Bodies
• Golgi complex
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5. CELL BODY (PERIKARYON)

6. • Multiple elongated processes
• Cytoplasmic~perikaryon (devoid golgi complex)
• Receiving stimuli
•Single process up to 100 cm
•Originate from axon hillock
•Devoid ribosome
•conducting impulse away from the soma
•It maintains Axonal transport

7. NEURONS CLASSIFICATION :
According to the size and shape of the processes
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8. NEUROGLIAL CELLS
• Metabolic and mechanical support for neuron
• Have phagocytic function
• 10 times abundant than neurons
• Neuroglial cells undergo mitosis
• CNS neuroglia Includes the following cell types :
1. Oligodendrocytes
2. Astrocytes
3. Ependymal Cells
4. Microglia
PNS neuroglia following cell types :
1- Schwann Cells
2- Setellite Cells
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9. CNS neuroglia Includes the following cell types :
1- Oligodendrocytes
– Produce myelin sheath (electrical insulation) in CNS
– A single cell wrap several axons (40 to 50)
– Form nodes of Ranvier
2- Astrocytes
– Pedicles binds to capillaries and to the pia mater form glial
limitans
– Controlling the ionic & chemical environment of neurons
– Energy metabolism
– Form cellular scar tissue
– Form the blood-brain barrier

10. 3- Ependymal Cells
• Low columnar ciliated epithelial cells  line the ventricles of the brain & central
canal spinal cord
• Formation of choroid flexus  produce CSF
• Facilitates the movement of CSF
4- Microglia
• Scattered throughout the CNS
• Clearing debris
• Act as APC
• Protect the CNS from viruses and microorganism

11. PNS neuroglia Includes the following cell types :
1- Schwann cells
• surround all axons of neurons in the PNS creating a neurilemma around them.
Neurilemma allows for potential regeneration of damaged axons
• creates myelin sheath around most axons of PNS
2 - Satellite cells
• support groups of cell bodies of neurons within ganglia of the PNS

12. •Grey matter consists of
neuronal cell bodies
 neuropil (dendrites and unmyelinated axons)
 glial cells (astroglia and oligodendrocytes)
•Grey matter contains neural cell bodies, in contrast to white matter,
which does not and mostly contains myelinated axon tracts.
•The color difference arises mainly from the whiteness of myelin
•White matter is composed of bundles of myelinated nerve cell processes.
•consists mostly of glial cells and myelinated axons that transmit signals from one region of
the cerebrum to another and between the cerebrum and lower brain centers.
•Its white color is due to its usual preservation in formaldehyde.

14. NERVE FIBERS
– Consist of axons enveloped by a special sheath
– Group of fibers constitute the peripheral nerve
– Two types :
1- Myelinated fibers
A single Schwann cell wraps around single axon form myelin sheath 
nodes of Ranvier
2 - Unmyelinated fibers
A single Schwann cell envelopes several axon
Fibers enveloped within simple clefts of Schwann cells

16. CONNECTIVE TISSUE INVESTMENTS OF NERVES
• Epineureum
– Dense collagenous Con. Tissue
with thick elastic fiber
– Prevent damage by
overstreching
• Perineureum
– Dense con. Tissue
– Layers of epithelioids
– Isolates neural environment
(blood-nerve barrier)
• Endoneureum
– Loose con. Tissue
– Regulation of
microenvironment of nerve
fiber
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17. GANGLIA
• Ovoid structure containing neuronal cell bodies, glial cells
supported by connective tissue
• Function : Relay stations to transmit impulses
• Types :
1- Sensory Ganglia (cell bodies of sensory neuron)
• Unipolar cell bodies enveloped by cuboidal capsule cells
– Cranial ganglia : Associated with the cranial nerve
– Spinal ganglia : Associated with the spinal nerve
2 -Autonomic Ganglia (cell bodies of postganglionic autonomic nerves)
• Multipolar neuron enveloped by satellite cells
• Some are located within certain organ (intramural)
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18. Sensory Ganglia Autonomic Ganglia

19. MENINGES
• The dura mater
– dense, collagenous connective
tissue
• The arachnoid layer:
– fibroblasts, collagen & elastic
fibers
– Layer in contact with dura mater
& a system of trabeculae
– Form arachnoid villi
• The pia mater
– Loose con. Tissue with blood
vessel
– There is a physical barrier
between pia mater & neuron
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20. Cerebellar Cortex
•Surface of cerebellum show transverse fissures which divide the cerebellum into a
number of lobules
.
•Section of cerebellar cortex shows three layers, from out to inside are:
1 - Molecular Layer. :
• Outer most layer mainly consists of cell processes.
•These cell process may be dendrites or unmyelinated axon.
•In this layer make the profuse synapses
2 - Purkinje Cell layer :
•This layer contains the cell bodies of large multipolar neurons called Purkinje cells.
•The purkinje cell consists large flask shaped body.
•cytoplasm contains large number of Nissl granules.
3- Granular Layer :
•This layer consists of thickly populated small cells called granule cells.
•This layer shows irregular scattered lighter staining area called as glomeruli or island.

21. Cerebellar Cortex