Lamellar Junctions In The Endolymphatic Sac Act As A Relief Valve To Regulate Inner Ear Pressure

Swinburne, I. A.; Mosaliganti, K. R.; Upadhyayula, S.; Liu, T.-L.; Hildebrand, D. G. C.; Tsai, T.; Chen, A.; Al-Obeidi, E.; Fass, A.; Malhotra, S.; Engert, F.; Lichtman, J. W.; Kirchhausen, T.; Betzig, E.; Megason, S. G.

doi:10.1101/143826

bioRxiv · 10.1101/143826

Lamellar Junctions In The Endolymphatic Sac Act As A Relief Valve To Regulate Inner Ear Pressure

Swinburne, I. A.·Mosaliganti, K. R.·Upadhyayula, S.·Liu, T.-L.·Hildebrand, D. G. C.·Tsai, T.·Chen, A.·Al-Obeidi, E.·Fass, A.·Malhotra, S.·Engert, F.·Lichtman, J. W.·Kirchhausen, T.·Betzig, E.·Megason, S. G.

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Abstract

The inner ear is a fluid-filled closed-epithelial structure whose normal function requires maintenance of an internal hydrostatic pressure and fluid composition by unknown mechanisms. The endolymphatic sac (ES) is a dead-end epithelial tube connected to the inner ear. ES defects can cause distended ear tissue, a pathology often seen in hearing and balance disorders. Using live imaging of zebrafish larvae, we reveal that the ES undergoes cycles of slow pressure-driven inflation followed by rapid deflation every 1-3 hours. Using serial-section electron microscopy and adaptive optics lattice light-sheet microscopy, we find a pressure relief valve in the ES comprised of thin overlapping basal lamellae that dynamically extend over neighboring cells before rupturing under pressure leading to ES collapse. The unexpected discovery of a physical relief valve in the ear emphasizes the need for further study into how organs control fluid pressure, volume, flow, and ion homeostasis in development and disease.

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Swinburne, I. A., Mosaliganti, K. R., Upadhyayula, S., Liu, T.-L., Hildebrand, D. G. C., Tsai, T., Chen, A., Al-Obeidi, E., Fass, A., Malhotra, S., Engert, F., Lichtman, J. W., Kirchhausen, T., Betzig, E., Megason, S. G.. 2017-05-30. Lamellar Junctions In The Endolymphatic Sac Act As A Relief Valve To Regulate Inner Ear Pressure. https://doi.org/10.1101/143826

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