▁govern ed ▁by ▁chem ot actic ▁factors ▁secret ed ▁from ▁Schw ann ▁cells . ▁In j ury ▁to ▁the ▁peri pher al ▁nerv ous ▁system ▁immediately ▁el ic its ▁the ▁migration ▁of ▁ph ag ocy tes , ▁Schw ann ▁cells , ▁and ▁macro ph ages ▁to ▁the ▁les ion ▁site ▁in ▁order ▁to ▁clear ▁away ▁de br is ▁such ▁as ▁dam aged ▁t issue ▁which ▁is ▁in hib itory ▁to ▁reg ener ation . ▁When ▁a ▁n erve ▁ax on ▁is ▁sever ed , ▁the ▁end ▁still ▁attached ▁to ▁the ▁cell ▁body ▁is ▁l abeled ▁the ▁proxim al ▁segment , ▁while ▁the ▁other ▁end ▁is ▁called ▁the ▁dist al ▁segment . ▁After ▁injury , ▁the ▁proxim al ▁end ▁sw ells ▁and ▁experiences ▁some ▁retro grade ▁deg ener ation , ▁but ▁once ▁the ▁de br is ▁is ▁cleared , ▁it ▁begins ▁to ▁spr out ▁ax ons ▁and ▁the ▁presence ▁of ▁growth ▁con es ▁can ▁be ▁detected . ▁The ▁proxim al ▁ax ons ▁are ▁able ▁to ▁reg row ▁as ▁long ▁as ▁the ▁cell ▁body ▁is ▁int act , ▁and ▁they ▁have ▁made ▁contact ▁with ▁the ▁Schw ann ▁cells ▁in ▁the ▁end one ur ium ▁( also ▁known ▁as ▁the ▁end one ur ial ▁t ube ▁or ▁channel ). ▁Human ▁ax on ▁growth ▁rates ▁can ▁reach ▁ 2   mm / day ▁in ▁small ▁n erves ▁and ▁ 5   mm / day ▁in ▁large ▁n erves . ▁The ▁dist al ▁segment , ▁however , ▁experiences ▁W aller ian ▁deg ener ation ▁within ▁hours ▁of ▁the