orthocortical cells ~3%: paracortical cells ~5 %
||Robbins, Clarence R. Morphological and macromolecular structure, pp.1-38, chapter 1 in the book Chemical and physical behavior of human hair / Clarence R. Robbins.-2nd ed (2002) p.17 2nd paragraph
|| Kassenbeck, P. In "Hair Research," Orfanos, Montagna, and Stuttgen (eds.), pp 52-64, Springer-Verlag, Berlin (1981). link
||P.17 2nd paragraph: "Most wool fibers contain two or even three types of cortical cells that are sometimes segregated into two distinct regions (Figure 1-16) that can be readily observed in cross section [ref 46]. These cell types are called orthocortex, paracortex, and mesocortex. Orthocortical cells contain less matrix between the microfibrils and a lower sulfur content (~3%): paracortical cells are smaller in diameter, and they have smooth and rounded borders and a high sulfur content (~5%) [primary source]. Mesocortical cells contain an intermediate cystine content [ref 93]." Primary source p.62 top paragraph: "In the orthocortical cells the microfibrils have much less sulfur-rich matrix between them and there are only a very few regions, mostly in the center of the macrofibrils, where the microfibrils appear to have a parallel orientation to the fiber axis. A similar situation is found in cortical cells of human hair (Fig. 15). Paracortical cells have a high sulfur content (~5%) and orthocortical cells a lower one (~3 %)."