Sections of tibia fixed in 4% paraformaldehyde and embedded in plastic were stained for ALP (A–C, E–G) activity to identify osteoblasts or for TRAP (B–D, F–H) activity to identify osteoclasts. Staining patterns were similar in 4-month-old Sam68+/+ (A and B), 4-month-old Sam68−/− (C and D), and 12-month-old Sam68−/− (G and H) mice compared with 12-month-old Sam68+/+ mice (E and F). Magnification at source, left panels ×10 and right panels ×40. Micrographs are representative of those taken from five to seven sections in each group of animals.