Path: Neurocytology and PNS path

Question 1

Histological characteristic of damaged neurons (actually schwann cells) that are trying to re-myelinate.

Answer 1

Onion bulb appearance

Question 2

Common histological presentation of muscle cells that are denervated.

Answer 2

Group atrophy

• this illustrates that multiple muscle fibers are innervated by just one nerve.
• seen in ALS

Question 3

Describe Wallerian Degeneration.

Answer 3

After an axon is transected, the distal portion degenerates and is “cleared” by macrophages.

Question 4

Describe Guillain-Barre Syndrome.

Answer 4

Inflammatory demyelinating disease that causes ascending paralysis by segmental demyelination.

Reflexes absent

Question 5

Describe Charcot-Marie-Tooth disease.

Answer 5

Hereditary demyelinating neuropathy that affects the fibular muscles and does not proceed above the knee. Results in pes cavus (abnormal arch in foot)

Question 6

Describe Dejerine-Sottas disease.

Answer 6

Demyelinating disease that affects the nerves innervating the trunk and limb muscles. Occurs in infants and is more severe and rapid in progression compared to Charcot-Marie-Tooth.

Question 7

How does diabetes lead to peripheral neuropathies?

Answer 7

Schwann cells (along with the lens and kidneys) use the polyol pathway as a major source of ATP which involves production of sorbitol.

In diabetics, the sorbitol accumulates due to excess glucose which increases the osmolarity inside the schwann cells.

Water rushes into the schwann cells and causes lysis.

Question 8

What condition is assoicated with Lambert-Eaton syndrome?

Answer 8

Small cell lung carcinomas

Question 9

What is neurocytology?

Answer 9

Study of CNS cells including: neurons, glia, meninges and cells composing vasculature

Question 10

When neurons are injured they can go thru chromatolysis which involves what?

Answer 10

Cell swelling
Dispersed Nissl substance
Nucleus marginalizing

Question 11

During neuron injury, intracellular inclusions can accumulate which are viewed on histology slides. What leads to:

1. Owl’s eye inclusion
2. Negri bodies
3. Lewy Bodies
4. Cowdry bodies
5. Neurofibrillary Tangles

Answer 11

1. CMV
2. Rhabdovirus
3. Parkinson Disease
4. Herpes Virus
5. Alzheimer Disease

Question 12

What are gemistocytic astrocytes?

Answer 12

Active astrocytes that are responding to neuronal injury.

Occurs in “astrocytosis” / “reactive gliosis”

Question 13

What do red neurons indicate?

Answer 13

Seen on autopsy of drowning victims. Indicates neuronal cell death due to hypoxia or anoxia.

Question 14

What part of the brain is most susceptible to hypoxia or anoxia?

Answer 14

Hippocampus