Comparison of the ordered densities within the OSER. A-D. The images were generated using the information in the masked Fourier transforms of the ROIs in the digitized micrographs, as described in "Materials and methods" (panels A-D show the cytosolic regions, whereas E shows the luminal regions); scale bar in E corresponds to 20 nm; all regions in A-E are scaled equally. The images with striation angles close to 90° are shown in A, whereas the regions with sharper striation angles are shown in B. An area in which two separate sets of striation overall producing a composite pattern is shown in C. An extended cytosolic region shows broadening of the spacing between the memrbanes, flanked by ordered densities (D). F-G. Geometric parameters of the ordered densities between OSER membranes indicate high degree of flexibility. F. The spacings between the striations (corresponding to the position of the strong reflection in the Fourier transform) were plotted for the identified cytosolic (black circles) and luminal (white circles) regions of interest; mean ± S.D. are shown in the graph. G. The distances between OSER membranes (d) were plotted against the angles between striations and membranes (α); an inset sketch indicates depicts the meaning of "d" and "α". Data points corresponding to the cytosolic and luminal regions of interest are indicated by solid and open circles, respectively.