I've always wondered... and so far have been unable to Google this: Does the non-nucleus part of a severed nerve cell die? If so, that would mean we only have a small window to "rejoin" severed CNS nerve cells, right? Nerve cells can be very long, I think up to a meter. I'd assume this includes spinal nerve cells of the CNS, which don't regrow. If the cells are severed, like in a spinal injury, that means there's a half-cell fragment with a nucleus, and the other half is the axon that's been cut away without a nucleus. Wouldn't the fragment without a nucleus shrivel up and die? That would be my intuition because I'd assume the nucleus is necessary to keep a cell alive.