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Changes in Müller cell plasma membrane specializations during subretinal scar formation in the rabbit
G E Korte1, G S Hageman, D V Pratt
1Department of Ophthalmology, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY 10467.
Abstract:
The aim of this study was to identify changes in Müller cell plasma membrane specializations during experimentally induced subretinal gliosis in rabbits. When rabbits are dosed with sodium iodate, large expanses of retinal pigment epithelium and photoreceptors are destroyed. They are replaced by a subretinal scar consisting mainly of the ascending processes of Müller cells. These processes transform from the slender, highly polarized structures seen in normal animals into irregular processes that form a glia limitans along the basement membrane of the pigment epithelium, left bare following its degeneration. As the scar processes extend through the subretinal space and contract this basement membrane, they undergo dramatic changes in shape that are especially apparent in three-dimensional computer reconstructions of serial thick sections examined by high-voltage electron microscopy. Other changes involve the intercellular junctions and apical microvilli normally associated with the external limiting membrane. These structures become scattered over the surfaces of the ascending processes and are eventually lost. Loss of microvilli is associated with disappearance of immunostaining for a specific glycoconjugate normally associated with the microvillar plasma membrane. The observations document profound changes in Müller cell structural and functional polarity during subretinal scar formation.
Insights
Subretinal gliosis in rabbits causes significant Müller cell changes. These retinal cells transform from polarized structures into irregular scar tissue, losing specialized membrane features.
Area of Science:
- Ophthalmology
- Cell Biology
- Neuroscience
Background:
- Müller cells are crucial glial cells in the retina.
- Subretinal gliosis involves scar formation behind the retina.
- Understanding Müller cell changes is key to retinal repair.
Purpose of the Study:
- To investigate Müller cell plasma membrane alterations during induced subretinal gliosis.
- To characterize the structural transformation of Müller cells in a rabbit model.
Main Methods:
- Experimentally induced subretinal gliosis using sodium iodate in rabbits.
- High-voltage electron microscopy of serial thick sections.
- Three-dimensional computer reconstructions.
- Immunostaining for specific glycoconjugates.
Main Results:
- Müller cell processes changed from slender and polarized to irregular.
- Formation of a glia limitans along the degenerated pigment epithelium basement membrane.
- Intercellular junctions and apical microvilli became scattered and were lost.
- Loss of microvilli correlated with reduced specific glycoconjugate staining.
Conclusions:
- Subretinal gliosis induces profound structural and functional polarity changes in Müller cells.
- These transformations impact the specialized plasma membrane structures of Müller cells.
- The study reveals significant cellular remodeling during retinal scar formation.