title: Endolymph movement visualized with light sheet fluorescence microscopy in an acute hydrops model.
abstract: There are a variety of techniques available to investigate endolymph dynamics, primarily seeking to understand the cause of endolymphatic hydrops. Here we have taken the novel approach of injecting, via a glass micropipette, fluorescein isothiocyanate-dextran (FITC-dex) and artificial endolymph into scala media of anaesthetized guinea pigs, with subsequent imaging of the inner ear using Light Sheet Fluorescence Microscopy (LSFM) as a means to obtain highly resolved 3D visualization of fluid movements. Our results demonstrate endolymph movement into the utricle, semicircular canals and endolymphatic duct and sac when more than 2.5 μl of fluid had been injected into scala media, with no apparent movement of fluid into the perilymphatic compartments. There was no movement of endolymph into these compartments when less than 2.5 μl was injected. The remarkable uptake of the FITC-dex into the endolymphatic duct, including an absorption into the periductal channels surrounding the endolymphatic duct, highlights the functional role this structure plays in endolymph volume regulation.
authors.affiliation: Sydney Medical School, The University of Sydney, Sydney, NSW, 2050, Australia. Electronic address: daniel.brown@sydney.edu.au.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Brown
authors.affiliation: Sydney Medical School, The University of Sydney, Sydney, NSW, 2050, Australia.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Pastras
authors.affiliation: Vestibular Research Laboratory, The University of Sydney, School of Psychology, Sydney, NSW, 2050, Australia.
authors.forename: Ian S
authors.initials: IS
authors.lastname: Curthoys
authors.affiliation: Sydney Medical School, The University of Sydney, Sydney, NSW, 2050, Australia.
authors.forename: Cassandra S
authors.initials: CS
authors.lastname: Southwell
authors.affiliation: University of Utrecht, Faculty Nature and Technique, Inst. for Life Sciences and Chemistry, Utrecht, 3508 AD, The Netherlands.
authors.forename: Lieke
authors.initials: L
authors.lastname: Van Roon
mesh_terms: D000818:Animals; D001835:Body Weight; D003051:Cochlea / Q000503:physiopathology; D003053:Cochlear Duct; D004487:Edema; D004710:Endolymph / Q000000981:diagnostic imaging* / Q000502:physiology; D018159:Endolymphatic Hydrops / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology; D008856:Microscopy, Fluorescence / Q000379:methods*; D010498:Perilymph; D012444:Saccule and Utricle / Q000503:physiopathology; D012665:Semicircular Canals / Q000503:physiopathology
keywords: Cochlea; Endolymphatic hydrops; FITC-dextran; Guinea pig; Light sheet fluorescence microscopy; Meniere's