Purchase this article with an account.
P. Gouras, L. Ivert, M. Neuringer, J. A. Mattison; Drusen Formation From the Basal Side of the Retinal Epithelium in Elderly Monkeys. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6157.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We are investigating how drusen form in aging monkey retina by examining the ultrastructure of young and old monkeys (Macaca mulatta)
Retinas of 7 old (24-30 years old) and 2 young (1 & 6 years old) monkeys were examined by electron microscopy. We focused on the basal membrane of the macular epithelium to test hypotheses about drusen formation, which propose that pieces of basal epithelium form the material in drusen. We examined 105 drusen and adjacent retinal areas.
Basal membrane from young animals had many folds that contacted the epithelial basal lamina. Mitochondria clustered near these folds. The folds were tightly apposed with little extracellular space between them. The basal lamina was straight, contacting straight strands of adjacent collagen fibers. Drusen were absent. In old monkeys, basal membrane formed folds but more extracellular space separated each fold. The basal lamina and adjacent collagen were more tortuous. Drusen were common, located between the basal lamina and the collagen layer. The material in drusen was mostly membranous with circular patterns resembling similar structures formed by folds in the epithelium. Degenerate epithelium and macrophage-like cells were found in drusen often in contact with the basal lamina. Breaks were found in the basal lamina showing a transfer of membranous folds into drusen.
The results support the idea that material in drusen comes from membranous folds transferred into drusen through breaks in the basal lamina. Whether all the material originates in this way is uncertain but the fact that drusen form central to the internal collagen layer implies that little material comes through Bruch’s membrane from the choriocapillaris. The greater amount of extracellular space between folds of old retinal epithelium may reflect defects in membrane transport, which the heavy clusters of mitochondria suggest is occurring here. Aging of these mitochondria may lead to defects in the basal side of the epithelium and to drusen formation.
This PDF is available to Subscribers Only