Immunohistochemical evaluation of fibrovascular and cellular pre-iridal membranes in dogs

Authors

  • Bianca S. Bauer,

    1. Department of Small Animal Clinical Studies, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada
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  • Lynne S. Sandmeyer,

    1. Department of Small Animal Clinical Studies, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada
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  • Riley B. Hall,

    1. College of Medicine, Health Sciences Building, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
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  • Bruce H. Grahn

    1. Department of Small Animal Clinical Studies, Western College of Veterinary Medicine, 52 Campus Drive, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B4, Canada
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Address communications to:
B. S. Bauer
Tel.: 306-966-7083
Fax: 306-966-7174
e-mail: bianca.bauer@usask.ca

Abstract

Objective  Histologically, two morphologically distinct types of pre-iridal membranes appear to occur in diseased canine globes: fibrovascular and cellular. Cellular pre-iridal membranes of corneal endothelial origin exist in iridocorneal endothelial (ICE) syndrome in humans and arise through metaplastic transformation of corneal endothelial cells into epithelial-like cells.1 The purpose of this study was to (i) evaluate immunohistochemical staining of these two types of membranes in diseased canine globes, (ii) determine whether endothelial cell metaplasia or iridal vascular budding plays a role in cellular membrane formation and (iii) compare the primary histopathologic diagnosis between the two groups.

Procedures  Hematoxylin and eosin (H&E)-stained slides of 28 enucleated canine specimens with pre-iridal membranes were randomly selected and examined with light microscopy. The globes were divided into two groups based on the appearance of the membrane: fibrovascular or cellular, and the histopathologic diagnoses were recorded. Immunohistochemical staining for vimentin, cytokeratin AE1/AE3, and Von Willebrand’s factor (Factor VIII) was completed on the slides of each globe. The histopathologic diagnoses were compared between the two groups.

Results  The fibrovascular and cellular membranes stained positive for vimentin and negative for cytokeratin AE1/AE3. All fibrovascular membranes stained positive for Factor VIII compared with the cellular membranes which stained negative. In the cellular membrane group, primary glaucoma was a common histologic diagnosis.

Conclusions  Immunohistochemical evaluation in this study does not support the hypothesis of metaplastic transformation of endothelial cells into epithelial-like cells in the canine globes with cellular membranes. The cellular membranes in this study do not represent a canine version of ICE syndrome and are not of vascular endothelial origin.

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