Download histology of nervous tissue

Histology of Nervous
Tissue
PROF. DR. FAUZIAH OTHMAN
DEPT OF HUMAN ANATOMY









Feature of nerves tissue
Type of cell: neuron & neuroglia
General feature of neuron
Type of neuroglia: astrocyte, oligodendrocyte,
ependymal cell, microglia
Synapses
Myelin – formation & function
General structure of peripheral nerves
Ganglia – dorsal root ganglia
& autonomic ganglia

Nervous system divided into:

Central nervous system (CNS)
Brain and spinal cord

Peripheral nervous system (PNS)

Cranial and spinal nerves – locate outside the CNS.
Morphology of typical neuron

Neuron functional cell of the nervous tissue.

Cell body or perikaryon - contains the nucleus – regulates
the functioning of the neuron.



Numerous dendrites and a single axon.
Contains Nissl bodies in the cytoplasm
Axon hillock- no Nissl bodies

Axon – cellular process (extension) – carries impulses away
from the cell body.

Dendrites – cellular process (extension) – carries impulses
toward the cell body
2 types of cell
i)
ii)
Neurons
(nerve cells)
Supporting cells
Functions of neurons
1)
2)
specialized to receive stimuli and to conduct electrical
impulses to other parts of the system.
Arranged as an integrated communications network, with
several neurons in a chain-like fashion involved in sending
impulses from one part of the system to another.
Neuron Classification

Structural:

Multipolar – most common type in CNS.


Bipolar- not as common purely sensory.


Include all motor neurons and interneurons of brain and
spinal cord.
Retina of eye, inner ear, olfactory epithelium in the
upper region of nose.
Unipolar (formerly known as pseudounipolar)

Sensory neurons found in numerous craniosacral ganglia
of the spinal cord.
Comparison of Structural Classes
of Neurons
Comparison of Structural Classes of
Neurons
Comparison of Structural Classes of
Neurons
Unipolar neuron
Nucleus &
nucleolus
Cytoplasm
fibrocytes
Satellite
cells
Cytoplasm of
neuron
Myelinated axons
The supporting cells (neuroglia or
glia):






Astrocytes
Oligodendrocytes
Microglial cells
Ependymal cells
Schwann cells
Satellite cells
CNS
PNS
Astrocytes



Largest, most numerous, versatile, and
highly branched glial cells
They cling to neurons and cover capillaries
Functionally, they:




Support and brace neurons
Anchor neurons to their nutrient supplies
Guide migration of young neurons
Control the chemical environment
Astrocytes
Microglia

Microglia – smallest, ovoid cells with spiny processes
- phagocytic cells that migrate through the CNS
remove foreign and degenerated material
and
Ependymal Cells

Ependymal cells – squamous- to columnarshaped cells

They line the central cavities of the brain and
spinal column
Oligodendrocytes

Oligodendrocytes – branched cells that wrap CNS
nerve fibers
- Produce myelin in CNS
Schwann Cells and Satellite Cells

Schwann cells (neurolemmocytes) – form myelin
sheaths around peripheral axons

Satellite cells surround neuron cell bodies with
ganglia
Synapse


A junction that mediates information transfer from one
neuron:
 To another neuron
To an effector cell
Presynaptic neuron – conducts impulses toward the synapse
Postsynaptic neuron – transmits impulses away from the
synapse



The region where the terminals come close to
another cell and transmit the impulse
Myelin – formation & function


1.
2.
3.
Whitish, fatty (protein-lipid), segmented
sheath around most long axons
Its function:
Protection of the axon
Electrically insulating fibers from one
another
Increasing the speed of nerve impulse
transmission
2 types of neuroglia produce
myelin


CNS= Oligodendrocyte
PNS= Schwann cells