Cell death in the rat retina after a pressure-induced ischaemia-reperfusion insult: an electron microscopic study. I. Ganglion cell layer and inner nuclear layer.

In rats, a pressure-induced ischaemia-reperfusion insult can lead to retinal cell death. In order to elucidate the underlying mechanisms, we performed a qualitative study of the ultrastructural morphology of degenerating retinal cells in the ganglion cell and inner nuclear layers at several time points after the insult. Three morphologically distinct types of cell death could be individualized. Type I was characterized by progressive karyo- and cytolysis and was consistent with necrosis. Type II exhibited progressive shrinkage and condensation of the nuclear and cytoplasmic components followed by heterophagic elimination, thus resembling apoptosis. Type III was characterized mainly by homogenization of the nucleoplasm and cytoplasm and dilation of the perinuclear cisternae and endoplasmic reticulum, thus showing features of 'non-lysosomal vesiculate' cell death. This study lends support to the concept that there may exist a fair but limited number of types of cell death in the retina.