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Peter Gouras, Lena Ivert, Martha Neuringer, Takayuki Nagasaki; Ultrastructural pathology of drusen in monkey retina. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2272.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the formation, composition and neighboring organelles of drusen in order to better understand the pathogenesis of age related macular degeneration in monkeys.
Electron microscopy was used to identify and study drusen and their neighboring organelles in three elderly rhesus monkeys. Observations involved segments along the vertical and horizontal meridians centered on the macula and extending to the ora serrata. 71 macular and 56 peripheral drusen were examined.
Drusen formed from protrusions of the basal membrane of the epithelium, which broke through the basal lamina to form extracellular deposits in Bruch’s membrane. Initially a druse was encircled by a reformed basal lamina enclosing cytoplasmic and membranous material. Then at what seemed to be a second stage, the basal lamina disappeared and the cytoplasmic material started to degenerate. At what seemed to be a final stage all the membranous debris in the druse was replaced by a homogenous granular material that occasionally contained autosomal vacuoles. Numerous multi lamellar bodies were also found in the basal regions of the epithelium suggesting that autophagy was occurring. The basal in folds of the epithelium tended to be lost adjacent to drusen. In nearby Bruch’s membrane processes of macrophages were seen which never went beyond the elastin layer.
This study has demonstrated that there are several types of drusen in aging monkey retina based on morphology. One contains much disorganized membranous and cytoplasmic debris thought to be an early stage. The other type contains fine homogeneous material thought to be a later stage. The fining of autosomal vacuoles and multi lamellar bodies in and around drusen implies that autophagy is occurring, perhaps of basal membrane in folds. Autophagy could explain the evolving changes in drusen morphology and also contribute to the pathogenesis of age related macular degeneration.
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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