TRAP-Stained Osteoclasts in Mouse Bone
Osteoclasts are difficult to identify in mouse bone. Therefore, it is recommended to stain for TRAP as a marker for these bone resorbing cells (yellow arrows). Since non-specific TRAP staining along bone surfaces is possible, TRAP-stained areas should be identified as osteoclasts only if nuclei are visible.
Fluorochrome Labeling of Cancellous Bone
Bone spicules (b) with double fluorochrome labels indicative of active bone formation are seen under UV illumination. The declomycin label (yellow arrows) was given at 10 days before sacrifice. The calcein label (red arrows) was given at 3 days before sacrifice.
Fluorochrome Labeling of Cortical Bone
Cross section of a murine femoral shaft under UV illumination with cortical bone (b) and marrow cavity (m). The outer periosteal surface (P) exhibits a double fluorochrome label consisting of calcein (yellow arrow) and tetracycline HCl (red arrow) labels. A calcein label (yellow arrow) is also seen along the inner endocortical (E) surface.
Cortical Bone in PTH-Treated Rat
Cross section of tibial diaphysis in aged female rat treated for 8 weeks with PTH. The hormone has augmented cortical bone mass (b) by stimulating deposition of layers of lamellar bone at the periosteal surface (red arrow). In addition, the marrow cavity (m) has been mostly filled by deposition of new bone (asterisks) extending from the original endocortical surface (green arrow).