system
Given the following post, respond as if you're commenting on Reddit:
human
From what I understand, we have a lot of trouble surgically reconnecting nerves. That being the case, how do transplants work? If we can't really reconnect nerves, how does the transplanted tissue function?
gpt
Nerves like those directing muscle movement - aka motor nerves, need to be in the right " orientation" because they map all the way into our spine and brain in a set pattern. A specific patch of your brain controls your pinky versus ring finger, but both are carried by the same nerve sheath in your wrist. Similar things are true for sensory nerves and preserved patterning. It's difficult to even connect these nerves surgically, let alone hypothetically ensure proper orientation.

Also, motor neurons do not regrow leasily. The cell body is located all the way a the spine, and cutting a distant part of it causes the nerve to undergo so much of a "shock" that it might die. They can regrow, but it's rare and we don't quite know how yet.

Many organs don't need nerves to function full - the might work on endocrine functions. Also, many organs are supplied by autonomic nerves - different from motor/sensory. These are basically "on/off" signals - or rather "faster/slower" signals that don't need a specific orientation to work. These nerves are also less complex, and tend to regrow somewhat easier. A lot of times, these nerves follow the vessels that supply the organ. Therefore connecting the organ circulation is sufficient to start the nerve regrowth.