Week 3

Nervous Tissue Pre-Lab 1

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Nervous tissue is a difficult tissue to study with a single method. Masses of nerve fibres in the CNS appear as an almost homogeneous material with H&E staining - indeed, they used to be called neuropil ("nerve-felt") once. Methods used to demonstrate fibres in the CNS usually do not show neuron bodies to advantage. In these pages, images taken with a variety of techniques have been used, all of which may not be in your slide box.

In this lab, we are limiting ourselves to being able to recognise some basic features of neurons. We begin with a section of the spinal cord.

Without the microscope, recognise the central, H-shaped grey matter.
Neuron bodies will be seen only in the grey matter.
The rectangle includes a part of the ventral (anterior) horn of the grey matter. Large motor neuron bodies are located here.

There will be other smaller neurons, but we shall pay attention to the larger ones.
Neuroglial cells are not easy to identify at this stage, and you are not required to do so.

The black line drawn across the picture is the boundary between the grey and white matter. Five large neuron bodies are obvious here.
Observe the two bodies with nuclei. The nuclei are large, euchromatic and show a prominent nucleolus.
The cytoplasm is full of Nissl granules.

Try this :
1. What is Nissl substance?
2. Why are the nuclei of two other neurons not seen?
3. What is the clear space around the neurons?

Remember : With large neurons it is easy to mistake the large nucleus for the cell and the nucleolus for the nucleus! Do not fall into this trap!

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