Figure 1

Apoptotic OC (a-d). (a) An early stage TRAP +ve apoptotic OC that has detached from the resorption surface. Its cytoplasm is condensed and it is surrounded by space due to cell shrinkage (×1000). (b) An early stage apoptotic OC with cytoplasmic TRAP (red) and nuclear ISEL (grey) staining (×1000). (c) Late stage apoptotic OC with intense cytoplasmic TRAP staining and condensed, fragmented nuclei which are positive for ISEL (×1000). (d) A typical apoptotic OC with intense cytoplasmic TRAP staining, a condensed cytoplasm and condensed positive nuclei stained with DAPI (×1000). Expression of TRAP/ED1 in bone marrow cells (e-h). (e) In the tibia of vehicle treated rats there were only occasional TRAP +ve BMC (×200). (f) A single treatment with 10 μg/kg 1,25-(OH)₂D₃ gave rise to a significant increase in the number of TRAP +ve BMC (×200). (g) TRAP +ve BMC located in the bone marrow (×1000). (h) TRAP/ED1 +ve BMC located in the bone marrow (×1000): TRAP expression in the secondary spongiosa (day 4) (i-l). Tibiae from (i) vehicle and (j) 1,25-(OH)₂D₃ treated rats (2 μg/kg) and vertebrae from (k) vehicle and (l) 1,25-(OH)₂D₃ treated rats (2 μg/kg) (magnification: ×200). Expression of TRAP in the secondary spongiosae (day 6) (m-p). Tibiae from vehicle (m) and 1,25-(OH)₂D₃ treated rats (2 μg/kg) (n) or vertebrae from vehicle (o) and 1,25-(OH)₂D₃ treated rats (2 μg/kg) (p) (magnification: ×200): Expression of TRAP/ED1 in bone tissue (q-t). ED1 immunostaining show (q) ED1 +ve viable OC (×1000). Double staining for TRAP and ED1 show (r) both positive viable OC for TRAP (red) and ED1 (grey). ED1 is richest in the clear zone of OC (×400). (s) TRAP +ve viable OC (×1000), and (t) TRAP +ve OC together with periosteal cells weakly +ve for TRAP (×400).