Histology of the CNS

Question 1

What are neuroglial/ glial cells?

Answer 1

non-excitable, supporting cells of the CNS

Question 2

Name the 4 types of neuroglial cells of the CNS

Answer 2

Astrocytes (fibrous and protoplasmic)
Oligodendrocytes
Microglial cells
Ependymal cells

Question 3

What are the functions of astrocytes?

Answer 3

• Structural support
• Protection - glia limitans forms a barrier limiting the penetration of substances
• Maintains extracellular environment
• Reactive gliosis - scar tissue formation

Question 4

What is the difference between protoplasmic and fibrous astrocytes?

Answer 4

F- in white matter
P- in grey matter

F- long cytoplasmic processes (little branching)
P- short CP (a lot of branching)

F- End feet around blood vessels
P- End feet around nerves + blood vessels

F- many intermediate filaments
P- Fewer IF

Question 5

What is the function of Oligodendrocytes in White and Grey matter respectively?

Answer 5

• White matter – cells form myelin sheaths
  around axons.
• Grey matter – form satellite cells around
  neuronal cell bodies

Processes wrap around multiple axons several times to form lamellae.

Question 6

What is the function of microglial cells?

Answer 6

Macrophages of the CNS. Detects and eliminates threats like pathogens, damaged neurons, and cellular debris

Question 7

Function of ependymal cells?

Answer 7

• Form a protective
  barrier (zonulae
  occludens between
  cells).
• Produce cerebrospinal
  fluid (choroid plexus
  epithelium)

Question 8

Where are ependymal cells found?

Answer 8

• Ventricles of brain.
• Central canal of spinal
  cord.

Question 9

Structure of ependymal cells?

Answer 9

• Cuboidal or columnar
  cells.
• Surface facing the
  lumen has motile cilia
  or microvilli depending
  on location of
  ependymal epithelium

Question 10

What are Tanycytes?

Answer 10

Modified ependymal cells that line 3rd + 4th ventricles. They transport substances between CSF and blood capillaries.

Question 11

What does white matter consist of?

Answer 11

• myelinated
  (medullated) axons.
• neuroglial cells
• small blood vessels.

Question 12

What does grey matter consist of?

Answer 12

• Neuronal cell bodies.
• Neuroglial cells.
• Neuropil – meshwork of axonal, dendritic &
  neuroglial processes.

Question 13

What are the 6 layers of the cerebral cortex?

Answer 13

1) Molecular
2) External granular
3) External pyramidal cell
4) Internal granular
5) Internal pyramidal
6) Fusiform

+ layer

Question 14

What is the function of the hippocampus

Answer 14

Learning, memory, instinct

Question 15

What are the 3 main structures that form the hippocampus formation?

Answer 15

-Hippocampus proper
-Dentate gyrus
-Subiculum

Question 16

Why is the histology of the Hippocampus proper clinically important?

Answer 16

It is used to diagnose Rabies.

Negri bodies = Rabies confirmation

• Negri bodies are cytoplasmic
  inclusions in neurons.
• Negri bodies are composed of rabies virus proteins and RNA.

Question 17

What are the layers (strata) of the hippocampus proper?

Answer 17

• Ventricular ependyma.
• Stratum alveus.
• Stratum oriens.
• Stratum pyramidale.
• Stratum radiatum.
• Stratum lacunosum.
• Stratum moleculare.
  OR
  Strata lacunosum- moleculare
  (separate/ one layer depending on species)

Question 18

What is the function of the cerebellum?

Answer 18

Co-ordinates voluntary
movements and muscle
function in the
maintenance of normal
posture.

Question 19

What are the layers of the Cerebellar cortex?

Answer 19

• Molecular layer
• Piriform/Purkinje layer
• Granule cell layer

Question 20

What are the segments of the spinal cord?

Answer 20

cervical, thoracic,
lumbar, sacral,
caudal

Question 21

What are the 3 regions of the white matter in the spinal cord?

Answer 21

Dorsal, ventral and lateral funiculus