40 � 0 30 ..._ � u C 20 G) ::s D"' G) ... 10 LL 0 0 HAIR CURVATURE IN JAPANESE WOMEN N = 8926 fibers (from 132 volunteers) I I I I 50 0 ,, I \ I \ I I I I I 0 I I I I I I I I I I I 0 I \ \ q I \ \ \ 100 ------ Major axis --0-- Minor axis 150 200 Hair diameter/ 1,1m 325 Figure 5. Distributions of the major and minor axes of the hair diameter. The major and minor axes of the hair diameter were measured with 8926 fibers from 132 volunteers, and the frequency profiles of the major and minor axes were obtained with a 10-µm interval. Closed circles with a solid line and open circles with a broken line show the data of the major and minor axes, respectively. � 0 ..._ � u C G) ::s D"' G) ... LL 16 N = 8926 fibers (from 132 volunteers) 12 8 4 0 u------....._ ____ ,..__ ___ ____.,__._._....-..;;::,.___...-.._,-.,,,.J 1.0 1.3 1.6 1.9 Ellipticity of hair diameter 2.2 Figure 6. Distribution of the ellipticity of the hair diameter (major axis/minor axis). The ellipticity of the hair diameter was calculated from the ratio of the major axis to the minor axis, and the frequency profile of the ellipticity was obtained with a 0.05-unit interval.

326 12 E u ...... 8"' :I ·-,n -c I! i: :I u JOURNAL OF COSMETIC SCIENCE ◊ N = 132 volunteers R = 0.24 p = 5.9 X 10"'3 0 ,...._ ______ ___,_________,_ 1 1 _______ ___. 1.0 1.2 1.4 Ellipticity of hair diameter 1.6 Figure 7. Relationship between the measured curl radius and the ellipticity of the hair diameter. The mean curl radius and the mean ellipticity for each volunteer were obtained with ten hair fibers and plotted. The correlation coefficient (R) and p-value (p) for the slope of the approximated line were obtained, based on regression analysis. diameter. The correlation coefficient (R) and p-value (p) for the slope of the approxi­ mated line were obtained, based on regression analysis, and shown in Figure 7. The slight correlation between the curl radius and the ellipticity was observed, but the correlation was not high because individual differences were large in the case of Japanese women. This tendency is basically the same as that reported for the comparison between the human groups. TEM OBSERVATIONS OF INTERNAL FIBER STRUCTURE The transverse cross sections of typical highly curved hairs (0.6-1.0-cm curl radius) of Japanese women were treated with the two staining methods mentioned above to investigate their internal structure by TEM observation. Figure 8 shows the typical TEM images of a curved hair (curl radius: ca. 0.6 cm) stained with erythrosine B. In this staining method, macrofibrils and exocuticles are observed to be darker. The darkest spots in the images in Figure 8 are melanin granules (circular particles), and the dark lines are wrinkles of the specimen. Morphological differences in macrofibrils were clearly observed between the outer and inner regions of the curved shape. The macrofibrils in the outer region were relatively smaller and dispersed in inter-macrofibrillar material (Figure Sa). In contrast, the macrofibrils in the inner region were relatively larger and fused together (Figure 86). Interestingly, the morphological difference in the macrofibrils is similar to the difference between ortho- and paracortical cells in Merino wool (5 ). The ortho- and paracortical cells are located in the outer and inner regions of the crimped shape of the wool fiber,