“…Remarkably, there is insufficient human hair structural biology information known to provide a fundamental understanding of hair curvature. In contrast, substantial progress in sheep wool fiber structural biology (Rogers, 1959a,b;Bradbury, 1973;Kaplin and Whiteley, 1978;Orwin, 1979a,b;Marshall et al, 1991;Bryson et al, 2001;Caldwell et al, 2005a,b) reveals a strong correlation between the lateral distributions and abundances of para-, meso-, and orthocortical cell types and single fiber curvature (Horio and Kondo, 1953;Fraser and Rogers, 1955;Whiteley and Kaplin, 1977;Kaplin and Whiteley, 1978) and fiber diameter (Orwin and Woods, 1980;Orwin et al, 1984). Transmission electron microscopy (TEM) has revealed that cortical cell types are differentiated by morphological and/or structural variations in distinct subcellular components, namely: the intermacrofibrillar material (IMM), the cytoplasmic remnants (CR), the macrofibrils (Mfs), and the Mf components: the intermediate filaments (IFs) or trichocyte (hard a-keratin) proteins, embedded in a matrix material composed of keratin associated proteins (KAPs).…”