Figure 5.

(a) Gradient reverse images of the fibre cell walls and indent patterns in the inner region, the transition region, and the ‘outer’ region of the fibre cap. (b) Indentation modulus and hardness of the cell walls measured from the lumen to the middle lamella (ML) for the fibres in the three aforementioned positions of the fibre cap. Owing to the irregular shape of the fibres, data points are shown according to their relative position between lumen (0) and middle lamella (1) on a normalized x-axis.