<P> The lengthwise partition that divides most of the cochlea is itself a fluid - filled tube , the third duct . This central column is called the cochlear duct . Its fluid , endolymph , also contains electrolytes and proteins , but is chemically quite different from perilymph . Whereas the perilymph is rich in sodium ions , the endolymph is rich in potassium ions , which produces an ionic , electrical potential . </P>
<P> The lengthwise partition that divides most of the cochlea is itself a fluid - filled tube , the third duct . This central column is called the cochlear duct . Its fluid , endolymph , also contains electrolytes and proteins , but is chemically quite different from perilymph . Whereas the perilymph is rich in sodium ions , the endolymph is rich in potassium ions , which produces an ionic , electrical potential . </P>
what is the fluid-filled space behind the oval window
what is the fluid-filled space behind the oval window
cochlear duct
cochlear duct