[Scanning electron microscopic observation of the collagen fibrillar network in Bruch's membrane by cell maceration]

Cellular elements, including retinal pigment epithelia, were removed by the cell maceration method to obtain a three-dimensional view of the collagen fibrillar networks of Bruch's membrane. A bird's eye view of the inner collagenous zone of Bruch's membrane was obtained using the eyes of albino rabbits and Japanese monkeys. The eyes were treated with a low concentration of NaOH for several days and then observed with a scanning electron microscope. This procedure allowed the exposed inner collagenous zone of Bruch's membrane to be observed. In addition, the outer collagenous zone was also be observed in some of the specimens. Both zones were formed by dense lattices of fine collagen fibrils, and these fibrils frequently formed bundles in the outer collagenous zone. In the posterior poles of the eyes obtained from Japanese monkeys, a network of wavy fine collagen fibrils was observed. In both outer and inner collagenous zones, most of the collagen fibrils ran parallel to the retina. Fenestration of the sheet-like elastic layer was frequently observed through gaps in the thin collagen fibrillar network of the inner collagenous zone. The method employed in this study was considered suitable to obtain a wide bird's eye view of the collagenous zone of Bruch's membrane.