X-ray Diffraction Studies of Cell Membranes
For X-ray diffraction studies one requires a repeating pattern of structure that is both regular and extensive and the diffracting system must constitute a large proportion of the specimen exposed to the X-ray beam. A few membrane systems fulfil the requirements in the natural state. So far the nerve myelin sheath has provided the most detailed X-ray diffraction patterns, and these have been interpreted (Finean and Burge 1963) to provide an outline of molecular organization that may be of general significance in membrane structure. Electron microscope studies of mammalian tissues indicate that retinal rods and cones should provide a diffracting system if the retina can be suitable exposed. In some tissues such as muscle and kidney, mitochondria tend to be elongated, aligned, and close packed, and the tristae fairly regularly and closely spaced so as to provide a possible diffracting system, but diffraction studies of mitochondria in intact hydrated tissue have not yet been reported. The studies reported by Worthington (1960) were of mitochondria in intact but dried insect flight muscle.
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