Fig. 7. Although centrifuged to concentrate structural elements, this human vitreous specimen contains no membranes or membranous structures. Only collagen fibrils were detected. There were also bundles of parallel collagen fibrils such as the one shown here in cross section (arrow). (Sebag J: The Vitreous--Structure, Function and Pathobiology. New York, Springer-Verlag, 1989)