Morphological changes of retinal pigment epithelial and glial cells at the site of experimental retinal holes

Abstract

To investigate morphological changes of retinal pigment epithelial (RPE) cells and glial cells in the immediate and early phases of restoration at the site of experimental retinal holes. We made 0.2-disc-diameter retinal holes with a vitreous cutter in albino rabbit eyes. To assess very early changes of RPE cells, the eyes were enucleated at 0,1,3, and 5 h postoperatively and observed by scanning electron microscopy (SEM). At 1,5, and 7 days after surgery, eyes were enucleated and prepared in thin and ultra-thin sections for observation by light and transmission electron microscopy (TEM). SEM showed the surface of the RPE cells lifting a few hours after surgery at the site of the retinal holes. The tissue filling the retinal hole was amorphous and homogeneous, as viewed by light microscopy. TEM revealed that this tissue consisted of glial cell processes containing many organelles. In addition, the cytoplasm of the cells was relatively dark, while the surface of the filling tissue continued smoothly to the internal limiting membrane. These findings suggested that these cell processes were parts of Müller cells. RPE cells and glial cells assembling at the site of the retinal hole may play an important role in retinal hole closure in this experimental model. In addition, RPE cells were morphologically changed in an immediate phase of restoration.