▁matrix , ▁mod ulation ▁of ▁neur om us cular ▁syn apt ic ▁activity , ▁and ▁presentation ▁of ▁ant ig ens ▁to ▁T - ly m ph ocy tes . ▁ ▁Char cot – Marie – To oth ▁disease , ▁Gu illa in – B arr é ▁synd rome ▁( ac ute ▁infl am mat ory ▁dem y elin ating ▁poly rad icul op ath y ▁type ), ▁schw ann om atos is , ▁chron ic ▁infl am mat ory ▁dem y elin ating ▁poly ne urop ath y , ▁and ▁le pro s y ▁are ▁all ▁ne urop ath ies ▁involving ▁Schw ann ▁cells . ▁ ▁Str ucture ▁ ▁Schw ann ▁cells ▁are ▁a ▁variety ▁of ▁gli al ▁cells ▁that ▁keep ▁peri pher al ▁n erve ▁fib res ▁( both ▁my elin ated ▁and ▁un my elin ated ) ▁alive . ▁In ▁my elin ated ▁ax ons , ▁Schw ann ▁cells ▁form ▁the ▁my elin ▁she ath . ▁The ▁she ath ▁is ▁not ▁continuous . ▁Ind ividual ▁my elin ating ▁Schw ann ▁cells ▁cover ▁about ▁ 1 0 0 ▁ μ m ▁of ▁an ▁ax on — equ ating ▁to ▁about ▁ 1 0 , 0 0 0 ▁Schw ann ▁cells ▁along ▁a ▁ 1 - m ▁length ▁of ▁the ▁ax on . ▁The ▁g aps ▁between ▁adjacent ▁Schw ann ▁cells ▁are ▁called ▁nodes ▁of ▁Ran vier . ▁▁ 9 - O - Ac et yl ▁G D 3 ▁gang li os ide ▁is ▁an ▁ac et yl ated ▁g ly col ip