Nerve endings permitted physical sensations, and were found at the end of nerves. Because Miranda Cleave's Ganger couldn't stabilise, her nerve endings weren't fused properly, and she couldn't feel heat.
The Gangers' nerve endings were programmed to be cut off in the event that they fell in acid, "like airbags being discharged", after which new Gangers would form. (TV: The Rebel Flesh)