Fourier and power law analysis of structural complexity in cornea and lens

The ordered pattern of type I collagen fibrils in the transparent cornea is an example of specialization in the formation of functional ultrastructure. In contrast, the disordered and amorphous distribution of cytoplasmic proteins in the transparent lens resembles the structure of most cells. While the organization of cytoplasmic proteins is often considered to be random, the compartmentalization of functional proteins in biological cells and the organization provided by cytoskeletal elements suggests that non-random patterns of organization are common. Attempts to quantify disordered, amorphous patterns of ultrastructure in cells and tissues have been unsuccessful, in part, because the cellular organization of structural proteins including collagen, keratin, cytoskeletal and crystallin proteins is complex. Characterization of the complex patterns observed in electron micrographs is a fundamental problem in structural biology. This paper reviews the use of Fourier and power law analyses of electron micrographs of cornea and lens as models for ordered and disordered ultrastructure of cells and tissues.