Perilymph sample origins.

<p>(A) Exposed guinea pig cochlea with a cochlear implant inserted into the basal turn of scala tympani and with the apex prepared for sequential fluid sampling. The green substance surrounding the apex is silicone adhesive (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0183374#sec002" target="_blank">methods</a>). The apex has been perforated and fluid efflux is accumulating on the hydrophobic surface, which can be collected with minimal contamination. (B) Calculated spatial origins for the first four 1 μL perilymph samples collected from the apex, based on the measured cross-sectional area (CSA) of the perilymphatic compartments. The first sample includes the apical portion of scala vestibuli where the samples are collected. Later samples take into account the unavailable volume occupied by the cochlear implant in the 1.3 to 8.3 mm region of scala tympani (ST). Fluid samples are also influenced by solute exchange with adjacent compartments as they travel up the cochlea (not represented in this figure).