Element analysis of hair fibres. There were no significant differences in the sulphur levels, an indicator of structural integrity of hair fibres, between guard hairs in AKR/J-hid/hid, BALB/cByJ+/+, SB/LeJ-Foxq1sa/Foxq1sa, and(c) C57BL/6 J+/+ mice. Levels were reduced in the club region of the hair fibres in all four strains compared with the middle and distal tips but these were not significantly different. Kruskal–Wallis test; Club P = 0.671; middle P = 0.946; tip P = 0.946. Error bars indicate standard deviation.