September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Aqueous Outflow Pathways That May Be Specially Organized to Sense Flow and Pressure
Author Affiliations & Notes
  • Murray A Johnstone
    Department of Ophthalmology, University of Washington, Seattle, Washington, United States
  • Yi Jiang
    Department of Ophthalmology, University of Washington, Seattle, Washington, United States
  • Steven Padilla
    Department of Ophthalmology, University of Washington, Seattle, Washington, United States
  • Chen Xin
    Department of Bioengineering, University of Washington, Seattle, Washington, United States
    Department of Ophthalmology, Beijing Anzhen Hospital, Capital medical university, Beijing, China
  • Elizabeth Martin
    Department of Ophthalmology, Cook County Hospital System, Chicago, Illinois, United States
  • Ruikang Wang
    Department of Bioengineering, University of Washington, Seattle, Washington, United States
  • Footnotes
    Commercial Relationships   Murray Johnstone, None; Yi Jiang, None; Steven Padilla, None; Chen Xin, None; Elizabeth Martin, None; Ruikang Wang, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 4707. doi:
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    • Get Citation

      Murray A Johnstone, Yi Jiang, Steven Padilla, Chen Xin, Elizabeth Martin, Ruikang Wang; Aqueous Outflow Pathways That May Be Specially Organized to Sense Flow and Pressure. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4707.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : To describe highly organized aqueous pathways that may sense flow & pressure.

Methods : Ex vivo primate (nemestrina) eye; radial SEM sections - complete 360O of limbus. Karnovsky’s fixative perfusion-IOP 8 mm Hg. SEM protocol optimized for SC (SC) endothelium (SCE) preservation, Segments (135), Images (755).

Results : Conduit-like pathways (CLP) arise from SCE to create a funnel-shape, then narrow to a cylindrical SCE-lined lumen that courses across SC to collector channel entrances (Fig. 1). Sections radial to the CLP funnel entrances in the juxtacanalicular space reveal a circular lumen composed of ring-forming scaffold cells (RSC). Funnel lumen interiors have 2 configurations: Type 1 (T1) lumens, (23 identified) contain sail-like cells (SLC) (Fig. 2B (*)). Cellular processes tether the SLC to the RSC. Type 2 (T2) lumens, (16 identified) have long cellular processes (LCP) spanning between RSC lumen walls (Fig. 2D). T2 lumens cut radially were measured: (n=9); width, 36.9±12.6 µm; height 21.8 µm±6.6 µm; area, 604.1±227 µm. In image in Fig. 2D, 57 total LCP were identified. In LCP close to the section surface (n=10): Mean length, 9.2±5.2 µm, R= 3.3-20.2 µm, mean minimal thickness, 131±34.4 nm, R= 79-198 nm. SEM reveals recurring highly organized CLP: T1 SLC present a large surface area to aqueous flow. Tethering of SLC to RSC walls by thin cellular processes assures both freedom of SLC movement and amplification of flow-induced forces at cell process-attachments to RSC walls. T2 lumen LCP span between RSC walls. IOP changes will increase RSC walls dimensions causing locally amplified forces at LCP attachments, a means of sensing pressure. Integrin signaling may provide local intrinsic regulation; the highly innervated region provides a means to couple sensory input to regional signaling pathways. The cochlea has structures somewhat similar dimensions, organization, and mechanisms to sense both fluid motion and pressure waves.

Conclusions : Our SEM protocol permits identifying highly organized conduits with 2 types of structures within their lumen, an arrangement somewhat analogous to the cochlea. T1 structures may permit sensing of flow by means of large sail-like cells that present a large surface area in the path of aqueous movement. T2 structures may permit sensing of pressure by means of prestressed processes suspended in a distending ring.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

 

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