Axon damage is one of the hallmarks in Multiple Sclerosis. My question is if I want to see axonal damage in mice model then what types of techniques and reagents I have to use?
You can use some neuronal markers or silver stain to label the neurons in tissue sections/slices and can quantify the reduction of neuronal staining. That's one technique.
Depending on the onset of the degeneration in your model, you can try to express GFP or axon-specific membrane targeted GFP by infection/electroporation of the areas you want to study. Then, once the disease has developed you'll have a good signal to follow axons and quantify their density between control and deseased tissue.