Comments on the paracrystalline nature of myelin

Varying degrees of distortion of the Q functions of myelin samples in different states - native, fixed, swollen, dehydrated etc. - suggest that disorder in the membrane system may appropriately be classified into intrinsic and nonintrinsic components. Quantitative estimates of the paracrystallinity in such biological systems (especially in the native state) from small-angle X-ray and neutron scattering experiments may not be directly correlated with similar measurements from electron microscopy. This is because preparative procedures for electron microscopy such as fixation and dehydration not only cause additional disorder but also induce in the membrane system structural changes which are not yet fully understood.