Fig. 1.

Confocal imaging of femoral bone sections following FITC-labelling. A,B) Large montages that span the endosteal (e) to periosteal (p) edges of cortical bone from young (A; age 22) and aged (B; age 78) female donors. Red boxes outline the cropped image that was used for segmentation and analysis. White dashed boxes are regions expanded in C—H. Greater resorption spaces are clearly evident in the sample from the aged donor (B; a few examples are labelled with pink asterisks). C,D) Close-up of the cortical bone microarchitecture (white box in A,B) showing larger vascular canals (vc) in the sample from an aged donor, similarly sized lacunae (lc), and greater canalicular (cn) density in the sample from a young donor. E,F) Vascular canal (blue), artifacts (yellow), and lacunae (red) masks applied, leaving only the green fluorescence from the canaliculi. G,H) Vascular canals, artifacts, and lacunae were black-filled and remaining image was converted to binary allowing quantitation of canalicular porosity. Scale bar in (A,B) is 500 μm and in (G,H) is 50 μm.