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Published on: April 3, 2016
Cartilaginous metaplasia in the sclera of Suffolk sheep
J D Smith1, A N Hamir, J J Greenlee
1Virus and Prion Research Unit, USDA ARS National Animal Disease Center, 1920 Dayton Avenue, PO Box 70, Ames, IA 50010, USA. Jodi.Smith@ars.usda.gov
Abstract:
Scleral cartilaginous metaplasia was detected by routine histologic examination of globes from 5 Suffolk sheep from a scrapie pathogenesis study. The extent of the metaplasia varied among the sheep but was always posterior to the tapetal fundus. The matrix surrounding chondrocytes stained intensely with alcian blue and was immunopositive for type II collagen. Retrospective evaluation of additional eyes from Suffolk and Cheviot sheep used in various scrapie pathogenesis studies at the authors' facility revealed similar histologic changes in 40% and 12.7% of eyes examined, respectively. The clinical significance of this previously unreported finding is unknown.
Insights
Scleral cartilaginous metaplasia was found in sheep eyes during scrapie research. This previously unreported finding involves changes in the sclera, but its clinical significance remains unknown.
Area of Science:
- Veterinary Pathology
- Ophthalmology
- Prion Disease Research
Background:
- Scrapie is a fatal neurodegenerative disease affecting sheep and goats.
- Ocular changes in scrapie are not well-characterized.
- Routine histologic examination is crucial for identifying pathological alterations.
Purpose of the Study:
- To report the incidental finding of scleral cartilaginous metaplasia in sheep.
- To characterize the histological features of this metaplasia.
- To determine the prevalence of this finding in sheep from scrapie studies.
Main Methods:
- Histologic examination of globes from Suffolk sheep involved in scrapie pathogenesis studies.
- Alcian blue staining to detect matrix components.
- Immunohistochemistry for type II collagen.
- Retrospective evaluation of additional sheep eyes.
Main Results:
- Scleral cartilaginous metaplasia was identified in 5 Suffolk sheep.
- The metaplasia occurred posterior to the tapetal fundus.
- Matrix stained positive for alcian blue and type II collagen.
- Prevalence was 40% in Suffolk and 12.7% in Cheviot sheep eyes.
Conclusions:
- Scleral cartilaginous metaplasia is a previously unreported finding in sheep.
- The observed metaplasia involves chondrocytes and a type II collagen-rich matrix.
- The clinical significance of this ocular finding in the context of scrapie pathogenesis is currently unknown.
