Abstract
Purpose::
CLANs are induced in trabecular meshwork cells in tissue culture and organ culture conditions by dexamethasone. These Factin-rich structures are of biological interest but may also be associated with pathological events in the outflow system. The distribution, incidence and characteristics of CLANs in unmanipulated normal and glaucomatous (POAG) trabecular meshwork is outlined for the first time in this study.
Methods::
The meshwork of 14 eyes ( 7 normal, 7 POAG) was studied by confocal microscopy by masked qualitative and quantitative analysis. Analysis of CLANs was conducted on dissected meshwork strips and 60um thick frozen sections stained for Factin with phalloidin alexa 488 and nuclei with propidium iodide.
Results::
We found CLANs in subsets of meshwork cells in all our specimens. They were more easy to identify in the uveal and corneoscleral meshwork than in the JCT. CLANs ranged in size and complexity from simple geometric arrangements with 2 or 3 polygonal units to network structures that had over 25 units and occupied a cytoplasmic territory of over 20 square microns. We conducted an analysis of over 750 CLANs reconstructed from equal samples from 8 eyes (4 POAG). There were more CLANs in the POAG samples (119.5 + 40.3) but they were also present in large numbers in the normals ( 71.5 + 20.5) so the difference did not reach significance.
Conclusions::
CLANs are of variable size and complexity. They appear to be present in greater abundance in the POAG meshwork but a more exaustive analysis is needed. However we have shown for the first time that populations of cells within the trabecular meshwork of all specimens examined have CLANs in their cytoplasm. As these are unmanipulated specimens then CLANs can no longer be considered a possible artefact of tissue or organ culture conditions.
Keywords: cytoskeleton • microscopy: light/fluorescence/immunohistochemistry • outflow: trabecular meshwork