Neurohistology

Question 1

What is an endothelial cell?

Answer 1

Endothelial cells line every blood vessel in the body

Question 2

Where are Purkinje cells found?

Answer 2

In the cerebellar cortex

Question 3

What is the average distance of the synaptic cleft?

Answer 3

10-40 nanometers

Question 4

What is the average diameter of a human axon?

Answer 4

1 micrometer

Question 5

What is the cresyl violet Nissl stain used to distinguish, and how is this done?

Answer 5

The cresyl violet Nissl stain is used to distinguish neurons from other types of cells in the brain (glia and Endothelial cells). This is possible due to the high density of rough endoplasmic reticulum (rER) found in neurons; called Nissl bodies.

Question 6

Explain how myelin stains are used

Answer 6

By staining the oligodendracyte endfeet, be underlying neuronal axons and tracts can be studied.

Question 7

What does the Golgi Silver stain reveal?

Answer 7

The golgi silver stain reveals the full morphology of neurons including dendritic trees and axons

Question 8

Name three applications of immunohistochemistry and describe how it works.

Answer 8

Immunohistochemistry is used to distinguish neuron from glia, differentiate the different glial cell types (astrocytes, oligodendrocytes and microglia), and to distinguish neuronal categories.

Immunohistochemistry works by selecting for particular antigens (proteins), by exploiting the principle that antibodies bond specifically to antigens (proteins).

Question 9

The Morphological classification of neurons is based upon which two factors?

Answer 9

Their external appearance and there topography (location)

Question 10

Where is endoplasmic reticulum found in neurons?

Answer 10

In the cell body and dendrites, but not the axon.

Question 11

How does the Nessus stain stain neurons and glial & endothelial cells differently?

Answer 11

The Nissl stain shows the nucleus and Soma of neurons but only the nucleus of glial and endothelial cells.

Question 12

Which molecular structures are detected in the nucleus and nucleolus and the ribosomes of the rER using the Nissl stain?

Answer 12

DNA and RNA in the nucleus and nucleolus, and RNA in the ribosomes of the rER

Question 13

What for the nucleus basalis in the base of the brain?

Answer 13

A cluster of neurons

Question 14

Name the five cytoarchitectural differences in the lamina

Answer 14

1. The size and density of neurons
2. The thickness of the layers
3. Neuronal morphology
4. Layers of neurons may be separated by layers which are richer in glial cells and myelinated neuronal processes
5. Connectivity input and output it to each layer differs

Question 15

What is found in the borders separating the six laminae of the cerebral cortex?

Answer 15

These borders are a relatively neuron free, they contain glia and neuronal axons.

Question 16

What is found underneath the six layers of cerebral cortex laminae?

Answer 16

Subcortical white matter

Question 17

Although they have distinct inputs and outputs, which two layers of the laminae are difficult to distinguish from each other?

Answer 17

Layers two and three. They contain medium sized, mainly pyramid or neurons.

Question 18

Which layer of the laminae contains an input layer from the thalamus, and is thick in sensory cortices?

Answer 18

Layer 4

Question 19

Which layer of the laminae contains some of the largest (generally) pyramidal neurons in the brain, such as in the primary motor cortex (Betz cells)?

Answer 19

Layer five

Question 20

Which layer of the laminae contains medium size neurons?

Answer 20

Layer 6

Question 21

Which layer of the laminae is very thin, without neuronal cell bodies? It contains myelinated neuronal processes (apical dendrites of pyramidal neurons and horizontally oriented axons), and has a high density of astrocytes?

Answer 21

Layer 1

Question 22

Explain what is fortuitous about the golgi Silver stain only labelling a few of all the neurons present in the CNS tissue

Answer 22

This allows us to get a more detailed view of those neurons that are stained, showing the full dendritic tree, soma shape, dendritic spines and axon. If too many neurons were stained we would not be able to make up this detail.

Question 23

How many times is a myelin sheath capable of encircling an axon?

Answer 23

More than 200 times