Fig. 2.

(a) Schematic of the quantitative polarised light microscopy (qPLM) system used in the study. The qPLM technique outputs three matching images: a grey scale intensity image I/I₀ that can be used to distinguish tendon zones (fascicles and the interfascicular matrix) (b), a false-coloured image of the phase shift |sin δ| that is directly related to tendon birefringence which in turn can be related to the directional dispersion of collagen fibres in a tissue (c) and a false-coloured slow axis orientation image φ (d) intensifying the visibility of collagen crimp and facilitating fascicle crimp length measurements. Moreover the combination of c) and d) enables collagen crimp angle measurements without the sectioning artefact resulting from the unknown relationship between the sectioning and crimp propagation planes (details in 2.3, 2.4). The typical images from the three channels shown above were taken from an unstained SDFT section of a young horse (b–d). Scale bars = 100 µm.