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7/31/2019 5. Lecture on the Histology of Cerebrum and Meninges by Dr. Roomi
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HISTOLOGY OF NERVOUS TISSUE
BY
DR. MUDASSAR ALI ROOMI (MBBS, M. PHIL)
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Cerebrum is the
largest part of brain.
Histolgically, Cerebral
cortex varies in
different parts of the
cerebrum
Allocortex: simplestcortex. it has got only
two layers e.g. the
olfactory cortex.
Neocortex: consists ofsix superimposed
layers. Most of the
cortex is of this type.
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Like cerebellum, the cerebrum also has a cortex
of grey matter on the surface and inner whitematter.
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Cells of the cerebral cortex
Pyramidal cells
Non-pyramidal cells:
1. Stellate cells (granule cells)2. Horizontal cells
3. Martinotti cells
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Pyramidal cells
Multipolar neurons
Pyramid shaped cell bodies
Large vesicular nucleus
Abundant Nissl granules in thecytoplasm
Dendrites: one main apicaldendrite and run towards themost superficial layer ofcortex. Some other smalldendrites are also present.
Axon: arises from the centreof base and runs in the whitematter.
Small, medium and large-sizedpyramidal cells.
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Pyramidal cells
7/31/2019 5. Lecture on the Histology of Cerebrum and Meninges by Dr. Roomi
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Non-pyramidal cells
1. Stellate cells (also called as granule
cells because of their small size)2. Horizontal cells: found in the most
superficial layer
3. Martinotti cells: found in the
deeper layers.
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Layers of cerebral cortex
1. Molecular or plexiform layer: chiefly
composed of cell processes. Some
horizontal cells are also present.
2. External granular layer: contains small
pyramidal cells and numerous closely
packed stellate cells.
3. External pyramidal layer: composed
mainly of large pyramidal cells and some
granule cells
4. Internal granular layer: consists of closely
packed stellate cells. Nerve fibers makeouter Band of Baillarger.
5. Internal pyramidal layer or ganglionic
layer (Betz cells): contains large pyramidal
cells., stellate cells and Martinotti cells.
Nerve fibers make inner Band of Baillarger.
6. Multiform layer: it contains neurons of
many shapes. Pyramidal cells, stellate cellsand Martinotti cells
HORIZONTAL
CELLS
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7/31/2019 5. Lecture on the Histology of Cerebrum and Meninges by Dr. Roomi
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How to draw it!
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Cerebrum- identification points
Outer grey matter
having six layers
Pyramidal cells
Inner white matter
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MENINGES
The brain and spinal cordis invested by three C.T.coverings called as
meninges. Mater= mother
1. Pia mater, which is theinnermost.
2. Arachnoid mater, whichis external to pia mater.
3. Dura mater, which is theoutermost.
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MENINGES
AROUND BRAIN
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MENINGES
AROUNDSPINAL CORD
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DURA MATER
Dura= hard (latin word).
Is has got tough consistency
Composed of denseconnective tissue
The dura mater is alwaysseparated from thearachnoid by the thin
subdural space.
Inner surface of dura materis covered by lining of flatcells of mesenchymal origin.
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ARACHNOID MATER
arachnoeides= spiderweblike (Greek
word)
It Consists of thin layer of connective
tissue
It has two components: (1) a sheet of
connective tissue in contact with the dura
mater and (2) a system of loosely
arranged trabeculae containing fibroblasts
and collagen.
This trabecular system is continuous with
the deeper pia mater.
Surrounding the trabeculae is a large,
sponge-like cavity, the subarachnoidspace, filled with CSF.
This space forms a hydraulic cushion that
protects the CNS from trauma.
Both the surfaces of the arachnoid mater
are covered by continuous layer of flat
cells.
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ARACHNOID MATER (cont.)
The connective tissue of thearachnoid is said to beavascular because it lacksnutritive capillaries, but largerblood vessels run through it.
The arachnoid and the piamater are intimatelyassociated and are oftenconsidered a single membranecalled the pia-arachnoid(leptomeninges).
Infection of leptomemninges iscalled as meningitis
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ARACHNOID MATER (cont.)
In some areas, thearachnoid perforates thedura mater and protrudesinto blood-filled venoussinuses within the dura
mater. These CSF-filledprotrusions, which arecovered by vascularendothelial cells, are calledarachnoid villi.
Their function is totransport CSF from thesubarachnoid space intovenous sinuses.
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PIA MATER
Pia= delicate
It is a thin layer ofconnective tissue
adherent to the surface of
nervous tissue Towards the
subarachnoid space, thepia mater is lined by acontinuous layer of flat
cells that resembles themesothelial lining of thebody cavities.
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Slide show meninges