An intensity expression of optical diffraction from striated muscle fibres.

From a simple statistical argument, an intensity expression was formulated for optical diffraction from striated muscle fibres. In terms of the reciprocal space coordinate (phi, mu) which corresponds to the real space coordinate (r, phi, x)(the x-axis being parallel to the fibre axis), the intensity I(mu, phi) is given by (formula; see text) where R is the radius of a fibril, J1(z) is the first-order Bessel function, L(mu) is the Laue function for sarcomere repeat along the x-axis, F(mu) is the unit cell (or sarcomere) structure factor, psi(mu, phi) is the structure factor for fibril arrangement in the fibre, 2 delta 2 is the variance of out-of-register of fibrils in the x-axis, P is the total number of fibrils in the fibre and Peff is the number of fibrils in an effective range Reff of short range order in a cross-section of the fibre. The quantity psi(mu, phi) expresses the volume effect emphasized from formulation based on the Bragg plane concept. Simulation of the intensity distribution of diffraction lines will be given and an application of the model will be discussed. A reciprocal space representation will also be given of diffraction for a 'tilt' Bragg plane model.