Histology: Central Nervous System

Question 1

What are the cells of neuroectodermal origin?

Answer 1

• Neurons
• Glial Cells

Cells of neuroectodermal origin include neurons and glial cells (astrocytes, oligodendrocytes, ependymocytes).

Question 2

What are the cells of mesenchymal origin?

Answer 2

• Microglia/macrophages
• Meninges
• Choroid plexus

Cells of mesenchymal origin include microglia/macrophages, cells of the meninges, and cells of the choroid plexus.

Question 3

What is found in the cerebral cortex gray matter?

Answer 3

Cell bodies, synapses and dendrites

Question 4

What is found in the cerebral cortex white matter?

Answer 4

Myelinated axons

Question 5

Gray matter covers the white matter in the ___________

Answer 5

Cerebral Cortex - this is opposite in the spinal cord.

Question 6

What does Nissl stain stain?

Answer 6

Rough endoplasmic reticulum

Question 7

What are the characteristics of motor neurons (size, axon length, etc)?

Answer 7

– Large cell body
– Have long axons
– Nucleus with single large nucleolus
– Prominent Nissl substance

Question 8

What are the characteristics of interneurons (local circuit)?

Answer 8

– Small compact cell body
– Lack Nissl substance
– Short dendrites and small axons

Question 9

What is the role of the principal neurons?

Answer 9

They have long axons and transmit information over long distances - an example are the motor neurons

Question 10

What is central chromatolysis?

Answer 10

In response to destruction of axons - neuronal cell body balloons and nucleus is displaced to the periphery with the dispersion of the ribonucleoprotein

Question 11

Neurophagia

Answer 11

Damage to the cell body directly may lead to it beyond surrounded by microglial cells - commonly seen in viral infections

Question 12

Acute Neuronal Injury

Answer 12

Irreversible injury with cell body shrinkage and increased cytoplasmic eosinophilia and loss of nuclear chromatin

Question 13

Where is the nucleus seen in a ballooned neuron?

Answer 13

Still remains central

Question 14

Negri Body Association

Answer 14

Rabies

Question 15

Lewy Body Association

Answer 15

Parkinson’s Disease

Question 16

Hirano Body Association

Answer 16

Alzheimer’s Disease but also noted in normal individuals with aging

Question 17

Function of Astrocytes

Answer 17

Aid with structure and repair of damaged neurons

Question 18

What are the main types of astrocytes?

Answer 18

• Fibrillary

- Protoplasmic

Question 19

Fibrillary Astrocytes

Answer 19

White matter – majority with

numerous and extensive processes

Question 20

Protoplasmic Astrocytes

Answer 20

Gray matter – fewer branches

Question 21

Gliosis

Answer 21

A non specific nervous system reaction to injury and involves hypertrophy of astrocytes

Question 22

Function of Oligodendrocytes

Answer 22

Maintenance of function of myelin sheaths

Question 23

Are there glia in the peripheral nervous system?

Answer 23

NO. Schwann cells will perform the functions of the oligodendrocytes.

Question 24

What happens with loss of oligodendrocytes?

Answer 24

Leads to demyelination

Question 25

Microglia

Answer 25

Not “true” glia - they are monocytes that are CD68+ and act as phagocytic and Ag-presenting cells

Question 26

Where are microglia found?

Answer 26

Found evenly in the gray and white matter

Question 27

Ependyma

Answer 27

Specialized glia that line the ventricles and have cilia - no basement membrane is present though

Question 28

What is the function of ependyma?

Answer 28

Mainly as barrier between the brain and CSF

Question 29

Choroid Plexus

Answer 29

Made of folds of CSF secreting ependymal cells that protrude into the ventricles

Question 30

Pia Mater

Answer 30

Thin layer over the brain and the spinal cord