SUMMARY In a morphological survey of 73 human retinae spanning 9 decades, and including 20 retinae which were obtained from eyes enucleated for malignant melanomas, nodular excrescences were noted in the outer segments of rods with an incidence which increased with age. These structures were sectioned in both their vertical and horizontal axes and on electron microscopical examination were seen to result from the localised convolution of affected outer segments. The topographic morphology of such convolutions is described and their modes of formation are discussed.The process of ageing and its manifestations in the cells of the human retina has for some time been a major research interest in our laboratory. These studies include the electron microscopical examination of 73 human retinae obtained from both enucleations and cadaver eyes. This series contains specimens from each of 9 decades, the youngest eye being 19 years and the oldest 90 years. The detailed morphology of the photoreceptor cells, the pigment epithelium, and Briich's membrane have been investigated in order to establish control reference material for a future study of senile macular degenerations and inherited retinal dystrophies. We were interested therefore by a recent report purporting to show the fusion of the outer segments of juxtapositioned rod photoreceptor cells in the retina of a 47-year-old woman whose eye was enucleated because of the presence of a choroidal melanoma (Borwein et al., 1977). In the present paper morphological evidence shows that this suggested fusion of appositioned cells is an age-related process occurring within the outer segments of individual rods. MethodsOne of the commonest conditions that leads to enucleation of human eyes is malignant melanoma of the uveal tract. The retinae of 20 such eyes have been studied in the present survey, with an age Address for reprints: Dr John Marshall, Department of Visual Science, Institute of Ophthalmology, Judd Street, London WC1H 9QS range spanning 7 decades. The immediate postoperative procedures varied with the individual demands of participating centres. In most centres corneal discs were trephined for subsequent use in graft procedures. One centre required the dissection of the globe and the hemisection of the unfixed tumour so that samples could be processed for tissue culture as well as histopathology. In some cases intact globes were presented immediately after enucleation, and here transcorneal incisions were made in the sagittal plain before immersion in fixative.All eyes were fixed within minutes of enucleation by immersion in 100 ml of 0 3 M glutaraldehyde buffered in 0-1 M sodium cacodylate containing 10 mg/ml of calcium chloride with a final pH 7-4. Intact globes were progressively dissected in this solution, the cornea being removed at the sulcus sclerae after 5 minutes, the iris after a further 5 minutes, and the lens, ciliary body, and vitreous 20 minutes after the initial immersion.After a total of 1 hour in fixative all posterior eye cups were washed in 0-1 M ...
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