[Hereditary drusen of Bruch's membrane. II: Studies of semi-thin sections and electron microscopy results].

Examination of a bulbus from a patient with hereditary drusen of Bruch's membrane revealed gradual development of drusen from fingerlike and fungous projections of the basal membrane of the retinal pigment epithelium culminating in large deposits with a conspicuous radial and laminar arrangement. The granular material which formed the drusen contained cellular debris as well as fragments of the fibrous long-spacing collagen. Cells of the pigment epithelium proliferated as metaplastic glial cells with formation of a new stratum separating the layer of cones and rods from Bruch's membrane. Transmembranous fibrovascular proliferation from the choroid into the periretinal space was not encountered and does not seem to play a decisive role in the pathogenesis of the disease.