<prompt> ECF K levels are seen inEctolymphAqueous humourEndolymphVitreous humour  <response>: C Endolymph Endolymph is formed in the scala media by the stria vascularis and has a high concentration of K and a low concentrtion of Na. Cells in the stria vascularis have a high concentration of Na-KATPase. In addition, it appears that there is a unique electrogenic K pump in the stria vascularis, which accounts for the fact that the scala media is electrically positive by 85 mV relative to the scala vestibuli and scala tympani. 