||P.177 right column bottom paragraph: "The cochlea is organized in a manner that segregates the ionic environment presented to the sensory cells within this organ. It contains two major fluid-filled compartments, which hold the perilymph and endolymph (Fig. 1a ). The perilymphatic space contains a high Na+ and low K+ solution, similar to other extracellular fluids. In contrast, the apices of the cochlear epithelial cells face the endolymph, which has an opposite cationic composition of high K+ and low Na+. The endolymph is further characterized by the presence of a positive endocochlear potential of 80 to 100 mV."