Introduction to Neuropathology

Question 1

What is the main question you should ask regarding neurolocalization?

Answer 1

Is the problem general or focal

Question 2

What type of cells are ependymal cells?

Answer 2

Glia

Question 3

What cell serves the purpose of the fibroblast in the CNS?

Answer 3

Astrocytes

Question 4

There are no astrocytes in the _____________.

Answer 4

choroid plexus

Question 5

_________ are the largest and most metabolically active cells in the body.

Answer 5

Neurons

Question 6

________ are usually the largest neurons.

Answer 6

Motor neurons

Question 7

The size of the soma parallels the length of the ____________.

Answer 7

axons

Question 8

Like cancer cells, neurons have very prominent ___________.

Answer 8

nucleoli

Question 9

Hematoxylin stains ___________, while eosin stains ___________.

Answer 9

DNA and RNA; protein

Question 10

What is the general histologic appearance of the cortex?

Answer 10

The cortex has a lot of neuronal cell bodies (far denser than white matter), and you can often notice the different layers.

Question 11

Describe four main ways neurons react to injury.

Answer 11

• Ischemic neurons undergo necrosis
• Neurons with damaged axons undergo chromatolysis
• Viral particles can be taken up by neurons
• Storage and neurodegenerative disorders can lead to accumulated protein within cells

Question 12

What are Lewy bodies?

Answer 12

Accumulation of protein in the cytoplasmic area near the nucleus (often seen in the neurons of the substantia nigra)

Question 13

The neurofibrillary tangles of Alzheimer’s are better seen on ______ staining than H&E staining.

Answer 13

silver

Question 14

What enzyme catalyzes the reaction that produces amyloid plaques?

Answer 14

Beta-secretase (alpha secretase does not lead to plaques)

Question 15

Transecting an axon leads to ____________, a process called Wallerian degeneration.

Answer 15

necrosis of the axon distal to the cleavage

Question 16

Swelling of the neuronal cell body indicates ____________.

Answer 16

that an axon has been destroyed

Question 17

Why can the brain not fill in necrotic, emptied-out areas?

Answer 17

Because there is no collagen for cells to migrate on

Question 18

Oligodendrocytes have a ___________ look on histologic exam due to low levels of cytoplasm.

Answer 18

“fried egg”

Question 19

Although ependymal cells are similar to epithelium, there is one important cellular distinction. What is it?

Answer 19

Ependymal cells do not secrete a basement membrane! Instead, they have astral processes that extend into the brain.

Question 20

What immunostain (i.e., receptor antibody) binds to microglia?

Answer 20

CD68

Question 21

How can you differentiate myopathy from denervation?

Answer 21

Myopathy: elevated CK, proximal weakness, EMG changes
Denervation: normal CK, distal weakness, different EMG changes

Question 22

Judging by what you know about the relationship between soma size and axon length, will the soma of pyramidal cells be bigger or smaller than those of upper motor neurons?

Answer 22

Pyramidal somas will be smaller –their axons are much shorter than motor neuron axons

Question 23

True or false: neurons that undergo chromatolysis are going to die.

Answer 23

False! They often die, but many peripheral cells will bounce back and live again.

Question 24

Eosinophilia means ____________ cytoplasm.

Answer 24

pink

Question 25

Basophilia means ____________ cytoplasm.

Answer 25

purple/blue

Question 26

What kind of glia are a type of ciliated epithelium?

Answer 26

Ependymal cells

Question 27

How fast can regrowing axons grow (as in, how much length per day)?

Answer 27

Between 0.5 mm/day and 5 mm/day

Question 28

“Onion-bulb” demyelination is a type of ____________ demyelination.

Answer 28

segmental

Question 29

What kind of glia are radial glia?

Answer 29

Astrocytes

Question 30

What is GFAP and what cell does it stain?

Answer 30

Glial fibrillary acidic protein; it is found on astrocytes

Question 31

Differentiate perimysium and endomysium.

Answer 31

Perimysium: covering sheath around muscle
Endomysium: little sheaths that go between individual muscle fibers that carry capillaries

Question 32

What is DAC?

Answer 32

Dystrophin-associated complex –a group of proteins that assists dystrophin

Question 33

What is the role of phosphocreatine?

Answer 33

It serves as a source of phosphorus for creatine kinase (CK) to add to ADP; this allows for an extra source of ATP when supplies are low.

Question 34

Can a motor unit contain more than one type of muscle fiber?

Answer 34

No, motor units will either be all fast- or all slow-twitch fibers –not a mixture

Question 35

Describe the roles of endoneurium, perineurium, and epineurium.

Answer 35

Endoneurium is the small amount of matrix between axons in a bundle; perineurium is the material that connects different axons together within the bundle; and epineurium is the sheath around the axon bundle.

Question 36

Each segment of myelin represents how many Schwann cells?

Answer 36

One

Question 37

True or false: unmyelinated axons in the periphery are not in contact with Schwann cells.

Answer 37

False, every PNS axon is covered by a Schwann cell, but the Schwann cell is not spiraled around multiple times

Question 38

Defective regeneration of a PNS axon can lead to a ____________.

Answer 38

neuroma

Question 39

Distal neuropathy is thought to be caused by what basic problem?

Answer 39

inability of the body to meet the metabolic demands of the neuron (which is why it starts distally)

Question 40

Give an example of two disorders (or groups of disorders) that have an “onion-bulb” demyelination pattern.

Answer 40

• Degenerative demyelinating neuropathies

- Charcot-Marie-Tooth neuropathy

Question 41

Actin connects to the _________ lines.

Answer 41

Z