Why doesn't an injured spinal cord re-grow?

The chemistry of fireworks, can I safely eat one year old Christmas cake, why we don't fall out of bed at night, what the Universe is expanding into, the reason we have to remove laptops from bags at airports, why the spinal cord won't spontanteously regenerate, sleep apps, and the science of forgetfulness all go under Lester and Dr Chris's microscope for analysis this week! Like this podcast? Please help us by supporting the Naked Scientists