al ▁my elin , ▁const itut ing ▁over ▁ 5 0 % ▁of ▁the ▁total ▁protein ▁in ▁the ▁she ath . ▁P 0 ▁has ▁been ▁shown ▁to ▁be ▁essential ▁for ▁the ▁formation ▁of ▁compact ▁my elin , ▁as ▁P 0 ▁null ▁mut ant ▁( P 0 -) ▁m ice ▁showed ▁sever ely ▁aber rant ▁peri pher al ▁my el ination . ▁ ▁Although ▁my el ination ▁of ▁large ▁cal iber ▁ax ons ▁was ▁initi ated ▁in ▁P 0 - ▁m ice , ▁the ▁resulting ▁my elin ▁layers ▁were ▁very ▁thin ▁and ▁poor ly ▁compact ed . ▁ ▁Une x pected ly , ▁P 0 - ▁m ice ▁also ▁showed ▁deg ener ation ▁of ▁both ▁ax ons ▁and ▁their ▁surr ound ▁my elin ▁she ath s , ▁suggesting ▁that ▁P 0 ▁plays ▁a ▁role ▁in ▁maintain ing ▁the ▁struct ural ▁integrity ▁of ▁both ▁my elin ▁formation ▁and ▁the ▁ax on ▁with ▁which ▁it ’ s ▁associated . ▁ ▁P 0 - ▁m ice ▁developed ▁behavior al ▁def ic its ▁around ▁ 2 ▁weeks ▁of ▁age ▁when ▁m ice ▁began ▁to ▁show ▁signs ▁of ▁slight ▁trem bling . ▁ ▁G ross ▁in co ord ination ▁also ▁arose ▁as ▁the ▁animals ▁developed , ▁while ▁trem bling ▁became ▁more ▁severe ▁and ▁some ▁older ▁m ice ▁developed ▁conv ul sing ▁behav iors . ▁ ▁Despite ▁the ▁array ▁of ▁imp a ired ▁motor ▁behavior , ▁no ▁par al ysis ▁was ▁observed ▁in ▁these ▁animals . ▁ ▁P 0 ▁is ▁also ▁an ▁important ▁gene ▁expressed ▁early ▁within ▁the ▁Schw ann