Central nervous system: Histology
Summary
TLDRThis script explores the central nervous system (CNS), highlighting its key components: the cerebrum, cerebellum, brainstem, and spinal cord. It delves into the roles of neurons and neuroglia, emphasizing their functions in the nervous system. The script contrasts the CNS's white and gray matter, explaining their composition and appearance. It also discusses the meninges, cerebrospinal fluid, and various cell types, including astrocytes and microglia, detailing their unique characteristics and roles. The video provides a comprehensive look at the CNS's structure and function, crucial for understanding neurological processes.
Takeaways
- 🧠 The central nervous system (CNS) comprises the cerebellum, cerebrum, brainstem, and spinal cord.
- 🌐 Neurons are the fundamental working units of the nervous system, while neuroglia or glial cells provide support and protection.
- 🧬 Central neuroglia includes astrocytes, oligodendrocytes, endothelial cells, and microglia, whereas peripheral neuroglia includes Schwann cells, satellite cells, and other organ-associated cells.
- 🔍 The CNS is macroscopically divided into white matter, rich in myelinated axons, and gray matter, primarily composed of neuron cell bodies and dendrites.
- 👀 In the spinal cord, white matter is peripheral, and gray matter is central, creating an H or butterfly shape in cross-section.
- 🛡️ The meninges are connective tissue layers that envelop the CNS, with the dura mater being the thickest and outermost layer.
- 💧 The brain's ventricles and the spinal cord's central canal are filled with cerebrospinal fluid (CSF), produced by ependymal cells.
- 🔬 Astrocytes are the most abundant glial cells in the CNS, with processes that help form the blood-brain barrier and produce glial fibrillary acidic protein (GFAP).
- 🔍 Microglia are the immune cells of the CNS, capable of moving and migrating to remove damaged tissue and participate in immune responses.
- 🧠 Pyramidal cells are prominent in the cerebral cortex, integrating sensory information and initiating motor responses, characterized by a large cell body and a single axon.
- ⚖️ The cerebellar cortex has three layers: the white matter, the granular layer, and the molecular layer, with Purkinje cells situated between the molecular and granular layers.
Q & A
What are the main components of the central nervous system (CNS)?
-The central nervous system (CNS) consists of the cerebellum, cerebrum, brainstem, and spinal cord.
What is the basic working unit of the nervous system?
-The neuron is the basic working unit of the nervous system.
What role do neuroglia or glial cells play in the nervous system?
-Neuroglia or glial cells are non-neuronal cells that support and protect the nervous system.
What are the differences between white matter and gray matter in the CNS?
-White matter is composed of lipid-rich myelin sheaths covering axons, while gray matter consists mostly of neuron cell bodies, dendrites, astrocytes, and microglia.
How is the spinal cord's arrangement of white and gray matter different from the brain?
-In the spinal cord, white matter is mainly in the periphery, and gray matter is closer to the center, forming an H or butterfly-shaped appearance in cross-section, which is the opposite arrangement found in the brain.
What is the function of the meninges in the CNS?
-The meninges are layers of connective tissue that cover and protect the CNS, with the dura mater being the thickest and outermost layer.
What is cerebrospinal fluid (CSF) and what is its function?
-Cerebrospinal fluid (CSF) is a clear fluid that fills the ventricles of the brain and the central canal of the spinal cord, providing cushioning and support to the CNS.
What are the characteristics of astrocytes and how do they contribute to the blood-brain barrier?
-Astrocytes are star-shaped glial cells with long processes that surround capillaries, helping to maintain the blood-brain barrier by inducing and maintaining tight junctions between endothelial cells.
How do oligodendrocytes contribute to the CNS?
-Oligodendrocytes are glial cells that wrap around axons to form myelin sheaths within the CNS, aiding in the speed of nerve impulse conduction.
What is the role of microglia in the CNS?
-Microglia are the immune cells of the CNS, responsible for finding and removing damaged tissue and participating in the CNS immune response.
What are the characteristics of pyramidal cells and their role in the cerebral cortex?
-Pyramidal cells are prominent neurons in the cerebral cortex with a large, pyramid-shaped cell body and a branching dendritic system. They integrate sensory information and initiate voluntary motor responses.
How does the cerebellum's cortex differ in structure from the cerebral cortex?
-The cerebellum's cortex has a distinct three-layered structure with the molecular layer, a single layer of Purkinje cells, and the granular layer, which is different from the six-layered structure of the cerebral cortex.
Outlines
🧠 Central Nervous System Structure and Function
The Central Nervous System (CNS) is composed of the cerebellum, cerebrum, brainstem, and spinal cord. Neurons are the fundamental units of the nervous system, while neuroglia or glial cells provide support and protection. Glial cells are categorized into central neuroglia, which include astrocytes, oligodendrocytes, endal cells, and microglia, and peripheral neuroglia, which include Schwann cells, satellite cells, and others. The CNS is macroscopically divided into white and gray matter, with the former containing lipid-rich myelin sheaths and the latter primarily composed of neuron cell bodies and dendrites. The cerebrum and cerebellum have gray matter on the outermost layer, while the spinal cord has white matter peripherally and gray matter centrally, forming an H or butterfly shape in cross-section. The CNS is covered by meninges, with the dura mater being the thickest and outermost layer. The ventricles of the brain and the central canal of the spinal cord are filled with cerebrospinal fluid (CSF), produced by ependymal cells. Astrocytes are the most abundant glial cells in the CNS, with processes that extend in all directions, including foot processes that form part of the blood-brain barrier. They also produce glial fibrillary acidic proteins (GFAP), which can be used as a marker for immunostaining.
🔬 Microglia and Neurons in the CNS
Microglia are small antigen-presenting cells in the CNS, found in both white and gray matter, and are unique among glial cells for their ability to migrate to different parts of the CNS. They play a crucial role in finding and removing damaged tissue and are part of the CNS immune response. They can be visualized more easily using immunostaining techniques. Immunocytochemistry is a method where cells are immunostained after being isolated and suspended in liquid. Pyramidal cells are the most prominent neurons in the cerebral cortex, integrating sensory information and initiating voluntary motor responses. They are characterized by their large, pyramid-shaped cell bodies with an apex pointing towards the cortical surface. The cerebellum's cortex has three layers: the innermost white matter, the middle granular layer, and the outer molecular layer. Immunostaining can be used to clearly visualize Purkinje cells, which have large cell bodies, highly branched dendritic systems extending into the molecular layer, and axons extending through the granular layer.
Mindmap
Keywords
💡Central Nervous System (CNS)
💡Neuron
💡Neuroglia or Glial Cells
💡White Matter
💡Gray Matter
💡Meninges
💡Cerebrospinal Fluid (CSF)
💡Astrocytes
💡Microglia
💡Pyramidal Cells
💡Cerebellum
Highlights
The central nervous system (CNS) comprises the cerebellum, cerebrum, brainstem, and spinal cord.
Neurons are the fundamental working units of the nervous system.
Neuroglia or glial cells provide support and protection to the nervous system.
Central neuroglia includes astrocytes, oligodendrocytes, endothelial cells, and microglia.
Peripheral neuroglia includes Schwann cells, satellite cells, and organ-associated cells.
The CNS is composed of white matter and gray matter, differentiated by the presence of myelin sheaths.
White matter contains axons with myelin sheaths, while gray matter is rich in neuron cell bodies and dendrites.
The cerebrum and cerebellum have gray matter on the outermost part with white matter in deeper regions.
The spinal cord has white matter in the periphery and gray matter closer to the center, forming an H or butterfly shape in cross-section.
The spinal cord's dorsal horns contain sensory neurons, and the anterior horns contain upper motor neurons.
The CNS is covered by meninges, with the dura mater being the thickest and outermost layer.
Ventricles of the brain and the central canal of the spinal cord are filled with cerebrospinal fluid (CSF).
Ependymal cells line the ventricles and central canal and are responsible for producing CSF.
Astrocytes are the most abundant type of glial cell in the CNS and play a role in the blood-brain barrier.
Oligodendrocytes can be identified by their small, round, and condensed nuclei and are responsible for myelin sheath formation in the CNS.
Microglia are the immune cells of the CNS, capable of migrating to different parts to remove damaged tissue.
Immunocytochemistry is a technique used to visualize cells, such as microglia, after they have been isolated.
Pyramidal cells are prominent in the cerebral cortex, integrating sensory information and initiating motor responses.
The cerebellar cortex has three layers: white matter, granular layer, and molecular layer.
Purkinje cells are a single layer of neurons between the molecular and granular layers in the cerebellar cortex.
Transcripts
the central nervous system or CNS
consists of the cerebellum cerebrum
brain stem and spinal cord the neuron is
the basic working unit of the nervous
system and the neuroglia or gal cells
are the non- neuronal cells that support
and protect the nervous system the
central neurog Gia includes asites
oligodendrocytes endal cells and microa
the peripheral neuroglia includes Schwan
cells satellite cells and a number of
cells associated with specific
organs macroscopically the CNS is made
of white matter and gray matter the
difference in appearance is from the
lipid Rich myelin sheaths that cover the
axons present in white matter whereas
the gray matter consists mostly of
neuron cell bodies dendrites asites and
microgo
cells in this high power image of white
matter from the SP final cord the axons
are surrounded by clear white space
which is where the myin was present
before the tissue was processed to
create the slide the outermost portion
of the cerebrum and cerebellum consists
of gray matter with their white matter
present mainly in the deeper regions of
the brain on the other hand the spinal
cord has the opposite arrangement with
white matter mainly in the periphery and
gray matter mostly located closer to the
center forming an H or butterfly shaped
appearance when looking at a
cross-section of the spinal spal
cord in this low power image we can see
the spinal cords two posterior or dorsal
horns closer to the top of the image and
two anterior or ventral horns at the
bottom the dorsal horns contain mostly
Sensory neurons and the anterior horns
contain mostly upper motor neurons a
simple way of remembering the location
of the motor neurons is to remember that
most cars also have their Motors in the
front or anterior part of the car the
entire CNS is also covered by layers of
connective tissue called the meninges
the portion of the meninges that can be
seen in this low power image is the
duramater which is the thickest and
outermost layer of the
meninges the ventricles of the brain and
the central Canal of the spinal cord are
filled with cerebral spinal fluid or CSF
and have a lining of cuboidal or
columnar cells called a anal cells these
cells are responsible for producing
CSF if we take a closer look at the
cells we can also faintly see that the
endal cells can have cyia which helps
circulate the CSF within the central
Canal the endal cells can also have
microvilli but they're typically too
small to be seen with light
microscopy now let's take a closer look
at the border between the spinal cords
white matter and gray matter on the left
is the white matter where we can
identify many any of the purple stained
axons by the myin sheaths that leave a
white space that surrounds each
axon on the right of this image is the
gray
matter although neuron cell bodies can
vary a lot in overall appearance they're
still usually recognizable by their
prominent nuclei with distinct
nucleoli they're also usually much
larger than gleo cells the different
gleo cells can be difficult to identify
and differentiate from each other when
using an h& stain except for
oligodendrocytes oligodendrocytes can be
identified by their small round and
condensed nuclei their cell bodies
aren't easily seen because their
cytoplasm is unstained since it contains
a lot of GGI complexes which don't
absorb the stain oligodendrocytes have
many processes that extend and wrap
around axons to form the myin sheath for
axons within the CNS the peripheral
nervous systems myin sheaths are
produced by Schwan cells instead
the gray matter surrounding all the
cells is called the neuropil which
consists of a dense network of fibrous
cellular branches or processes from gal
cells and
neurons in the CNS the star-shaped
asites are the most abundant type of gal
cell they have many long processes that
extend in all directions from their cell
body many of the processes have enlarged
terminal ends called foot processes
which surround capillaries as part of
the bloodb brain barrier the foot
processes help induce and maintain the
formation of tight junctions between
endothelial cells asites also produce
structural proteins called gleo
fibrillary acid proteins or gaps these
proteins can be used as a unique marker
for immunostaining to help visualize
asites in tissue samples in this high
power image the gfap specific staining
makes it easier to see the asites in
brown as well as the foot processing
that surround capillaries as we can see
them near the top of this
image microglia are small antigen
presenting cells of the CNS that are
found in both white and gray matter they
have short branching processes that
actively move and are the only gal cells
that also migrate to different parts of
the CNS which helps them find and remove
damaged tissue as well as function as
part of the CNS immune
response similar to asites microglia can
be visualized more easily using
techniques like amuno staining
immunocytochemistry is a form of
immunostaining where the cells are
immunostained after they've been
isolated and suspended in liquid which
is why the microa in this image are the
only cells present and they're also
spaced out relatively
evenly the paramal cells are the most
prominent neuron in the cerebral
cortex these eant neurons integrate
sensory information and initiate
voluntary motor responses
they get their name from their large
pyramid-shaped cell bodies that have an
apex that points towards the cortical
surface of the CeX at the top of this
image at the Apex there's a large
branching dendrite that extends up
toward the cortical surface the sides of
the cell have much smaller dendrites
that Branch out to the sides and its
single axon extends from the base of the
cell to synapse with other cells in the
cortex or even deeper into the white
matter together the direction of the
axon and the large dendrite give paramal
cells their appearance of being
vertically arranged within the cerebral
cortex moving to the cerebellum at low
power the cortex has three layers seen
with an h& stain the innermost layer
that stained dark pink is the white
matter the purple middle layer and outer
light pink layer are both a part of the
gray matter the outer layer is the
molecular layer and the dark purple
layer is the granular layer if we zoom
in closer to the border of these two
layers we can see that it actually has
three layers because of a single layer
of neurons called pereni cells that sit
between the upper molecular layer and
lower granular layer immunostaining was
performed on this section of tissue in
order to see the pingi cells more
clearly by staining them dark brown
these neurons have very large cell
bodies with a highly branched dendritic
system that extends into the molecular
layer and an axon that extends down
through the granular layer which is
often hard to to see even with
immunostaining helping current and
future clinicians Focus learn retain and
Thrive learn more
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