The pictures that follow are from representative sections through the spinal cord and the brainstem. It is important to realise that these structures are rather small, and a slight variation in the plane of a section chnages the detail. It is not possible to compare similar sections from another source like congruent geometrical figures.

Sections taken from CNS material can be stained by different methods, and appearances of grey and white matter can differ. It is not intended here to give details of various methods. In general it may be said that in methods that use  staining of myelin present white matter as dark.

It is also pertinent to point out that tracts in the nervous system are not anatomically well-defined entities like peripheral nerves or other body structures. It can be said that a majority of the fibres of a given tract are located in a specific area, but at the periphery of the area its fibres intermingle with those of neighbouring tracts. This is especially so in the spinal cord. In the brainstem some of the major tracts can be located with confidence, whereas in the case of most others an approximate location is all that can be indicated. For accurate localisation of tracts one needs material prepared after experimental or pathological degeneration of tracts, and stained by appropriate methods.

In the sections that follow, the idea is to understand the location of deeper structures (nuclei and tracts) which are not discernible in surface views. These sections also give a correlation between external features and their appearance in cross sections. To this end, some features can be considered as "core material" for this understanding. These are highlighted in this part of the pictorial guide.

Once again, being able to identify the sections is a means to understand the organisation of the CNS, and the first step is getting the correct orientation. Ask yourself some simple questions like where the ventral and dorsal surfaces of a section are, what surface features correspond with the features of a section...

You can refer back to the brainstem views to compare the sectional features with those on the suface. It will also be of great help to have diagrams from your manual by your side.

As you gain an idea of the organisation, ask yourself functionally relevant questions to correlate theoretical knowledge.