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Kevin Curtiss, Cheryl Hann, Daniel Possin, Bingjie Wang, Elizabeth Martin, Mark Slaba, Murray Johnstone; New Insights Into Schlemm's Canal (SC) Structural Relationships Using Multiple Imaging Modalities and 3D Reconstructions. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4667.
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Transparent cylindrical tubes spanning between the trabecular meshwork (TM) and SC external wall may represent normal conduits for aqueous flow. Viscoelastic dilation of SC provides a light path that permits new techniques involving the dissecting microscope (DM), phase contrast (PC) and differential interference microscopy (DIC) to image the tubes. Nondestructive imaging is unable to define tissue composition or relationships to collector channel ostia (CCO). The destructive and laborious technique involving serial epon-embedded histologic sections of the same tissues were completed to characterize these parameters.
Macaca nemestrina monkey eyes (16) to develop techniques, Healon injection into SC in each quadrant, Karnovsky fixative, 250-500 u radial limbal segments, 80-power dissecting microscope (41 segments, oblique light, black background), PC (231 images in 30 segments), 1-2 u DIC sections (5,129 images in 33 segments), 1 u epon sections (356 serial sections in 1 specimen), Photoshop for Z axis merge of histologic stacks, ImageJ for 3D projections.
A radial 356 u segment of SC circumference containing 4 tubules was chosen for correlation of nondestructive techniques with imaging from 1u histologic sections. Findings: (DM) 4 white structures arose from SC inner wall as a funnel, developing into a cylindrical structure that then attached to SC external wall; (PC) 4 semitransparent structures with comparable dimensions, position and topography; (DIC) 4 structures arising from SC inner wall with walls that attained the appearance of a funnel with an optically empty lumen. The funnel walls and lumen were continuous with the walls and lumen of an optically empty cylindrical region attached to SC external wall; Histologic Sections: Tubular structures identified by nondestructive techniques arose from SC endothelium (SCE) in a funnel shape that developed into endothelial lined cylindrical structures traversing SC to attach to SC external wall; two attached between and two at the entrance of CCO. DM, PC and DIC images from other segments had an appearance like the segment selected for histologic sections.
Transparent cylindrical tubes identified by relatively rapid nondestructive imaging approaches using DM, PC and DIC corresponded with histologic sections. Tubes composed of endothelium arising from SCE in a funnel-shaped fashion transitioned to a cylindrical endothelial lined tube that traversed SC to attach between or at CCO.
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