The Structure and Chemistry of Human Hair 30 data, the complete super lattice and packing dimensions established from in vivo X-ray diffraction data.” In this context Figure 16 illustrates the radial projection of their proposed model consisting of eight tilted tetramers in which each tetramer consists of an offset parallel alignment of two coiled-coil α-helical dimers. This latter work was speculatively refined to present a further model illustrating the potential interlocking of eight perimeter tetramers within an IF cross-section.70 This latter model was supported not only by a comprehensive geometrical analysis, but one which was said to correlate exactly with all high and low X-ray diffraction data as shown in Figure 16. Even if separate evidence is obtained for the all-parallel organization, as fostered by Feughelman and his colleagues, it remains to be determined how exactly the dimers are arranged in 3D space within the KIFs of human hair. Figure 16. A surface lattice depiction by Feughelman et al.70 for the organization of structural elements within KIFs. It shows the radial projection a to h of 8 tetrameric units each consisting of two parallel coiled-coil dimers and tilted at ca. 7 degrees. The white segments represent the helical domains and the gray segmentsthe cystine-rich terminal domains.