Why can Ach be used in both preganglionic para/symphatetic synapses but not at postganglionic synapses?
Why is it that preganglionic sympathetic fibers are usually short, whilst pre parasympathetic fibres are usually long? (Is that because those pre para fibers associated to the 4th cranial nerves are scattered in the brain? But what about those related to sacral segments?)
Why are there only 14 pairs of white rami communicantes but 32/31 gray communicantes?

Thank you very much for your answers (if any)

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