Changes in fibronectin staining in the human lens during ageing and cataractogenesis

Abstract

The content and localization of fibronectin, an extracellular glycoprotein, in the serial sections of lenses of normal human donors and caractous patients of different ages were determined by the indirect immunoperoxidase staining technique. This was followed by the evaluation with quantitative morphometric analysis. It was shown that fibronectin was present in the area of cell contacts as single deposits of faint orange-brown stained material in the lens samples of young donors. The fibronectin level was raised in lens sections from aged donors. Its accumulation was detected mostly within the spaces of the lens fiber cells. At different stages of cataractogenesis a dramatic decrease of the fibronectin content was detected in the lens sections obtained from patients of different ages. A new linear spectrophotometric technique was developed for evaluation of the lens transparency, to correlate the lens capacity with corresponding histological data obtained from the immunostaining technique. Morphological studies performed further suggested that the lens fiber cell plasma membrane structures were deteriorated. This was observed as changes of fibronectin staining in the lens sections of different periods of human ageing and cataract development. It is concluded that a decrease of fibronectin staining in the human lens is an indication for the structural damage of the lens fiber cell plasma membranes during ageing and cataractogenesis.