Figure 4.

(A) Central part of shaft endosteum in a Tergazyme macerated knockout (KO) femur. The dark patches are all abnormal osteoid [this scene is shown as a 3D anaglyph (red cyan) image in supplementary Fig. 4A in Appendix S1]. (B) Endosteum in a Tergazyme macerated KO tibia. Dark osteoid surrounds blood vessel canals (white arrows) within an area showing a mineralising front with unfused mineralising centres. This is surrounded by resorption (labels Res). (C) Endosteum in a Tergazyme macerated KO femur. Dark residual osteoid surrounds blood vessel canals (white arrows). Individual canaliculi show as small black dots (too small to label) within the unfused mineralising centres. The fully mineralised back wall of a forming osteocyte lacuna lies near dead centre of image at point of black arrow. (D) Endosteum in a Tergazyme and H₂O₂ macerated KO femur. The additional treatment removes residual osteoid from the endosteal surface and lining the blood vessel canals (black arrows). An area with abnormal mineralising front (outlined with white asterisks ‘*’) is surrounded by resorption (Res). (E) Endosteum in a Tergazyme and hydrogen peroxide macerated wild‐type (WT) tibia at the same scale, showing mostly a fully mineralised, smooth surface with some shallow resorbed patches (Res: one area outlined with white asterisks ‘*’). The openings of the blood vessel canals (black arrows) show a fully mineralised surface. Surface osteocyte lacunae above labels ‘sol’. Some osteocyte lacunae are so superficial that their canaliculi lie in the plane of the fully mineralised (smooth) surface, showing as grey linear features in areas opposite points of white arrows. See also supplementary Fig. 4F in Appendix S1.