Abstract
Abstract: :
Purpose: Basal laminae (‘basement membrane') of different vessels have varied morphological features some of which have been implicated in the development of metastases. In the retina, many studies have been performed on the effect of disease processes on the morphology of vascular ‘basement membrane' but very little attention has been paid to specific features in the normal situation. Methods: Retinal as well as choroidal tissue from the posterior pole and the periphery of 3 human eyes with essentially normal retina (3 melanomas, 52, 72, and 96 years), and from one patient with Werner syndrome but with clinically unremarkable retina (age 47) was processed for electron microscopy. Results: The tissue preservation of surgical material varies. Thus, it was difficult to evaluate and compare the respective specimens. A typical basal lamina consisting of a lamina lucida and lamina densa was, however, consistently found around choriocapillaries and larger choroidal vessels. In contrast, the peri-endothelial region of retinal vessels revealed much more heterogeneity, and near the posterior pole frequently consisted of a fairly broad band of ‘amorphous' matrix in immediate contact with the endothelial cells, often with cavitations in its outer layers that were not seen in ‘basement membrane' of choroidal vessels. This was parrticularly obvious in the patient with Werner syndrome. Retinal vessels from the periphery demonstrated a fairly irregular ‘basement membrane' with more frequent foci of lamina lucida-like structures. Larger retinal vessels also showed – compared to rertinal capillaries – a more variable ‘amorphous' matrix with occasional areas of less dense collagenous tissue or laminated ‘basement membrane' structure. Conclusions: There are distinct differences in the morphology of vascular basal lamina among human retinal and choroidal vessels. At this time, the meaning and consequences of these differences remain unclear. The effect of aging and fixation in particular should be investigated further.
Keywords: anatomy • microscopy: electron microscopy • vascular cells