Behavior of retinal epithelium to bleb detachment versus retinectomy

Abstract

To compare the behavior of the retinal pigment epithelium to a bleb detachment versus removal of a segment of neural retina. A bleb detachment was performed on 14 adult pigmented rabbits. In seven rabbits, the neural retina was removed within the bleb detachment. The rabbits were followed for months after surgery by scanning laser ophthalmoscopy and post mortem histology using light and electron microscopy. Bleb detachment produces a transformation of the retinal epithelial layer that results in migration, enlargement of cell size and accumulation of large amounts of lysosomal material, resembling that found in Chediak-Higashi syndrome. Retinectomy causes migration of the epithelial cells, development of multiple layers with vacuoles but no accumulation of lysosomal material. The neural retina appears to exert a strong influence on the behavior of the retinal epithelial layer. Brief separation of the neural retina from the epithelium provokes a rapid transformation of this cell layer leading to migration of the cells and apparent faulty digestion of phagosomes, causing an enormous buildup of lysosomal debris. Removal of the neural retina also provokes retinal epithelial cell migration but no buildup of lysosomal debris occurs, presumably due to the absence of photoreceptor outer segments and consequently phagosomes. This migratory tendency, which appears to alter lysosomal degradation, could lead to apoptosis of these epithelial cells.