Figure 2.

Serum levels of tartrate-resistant acid phosphatase (TRAP) and histomorphometric analysis of osteoclasts in GF and SPF mice. (a) Serum concentrations of bone markers from GF mice and SPF mice were determined by enzyme-linked immunosorbent assay (ELISA). The level of TRAP-5b was significantly higher in SPF mice than GF mice. * p < 0.05, t-test (n = 6/group). (b) Representative images of TRAP-stained spongiosa. Alveolar bones from 8-week-old GF (top) and SPF (bottom) male mice were harvested, and sagittal sections were analyzed by TRAP staining. TRAP-positive osteoclasts lining bone with ≥3 nuclei designating an osteoclast (arrows). Scale bar = 50 μm. (c) Osteoclasts and bone surface (μm) were measured in the range of 450 μm × 400 μm based on the alveolar crest using ImageJ computer software (version 1.45, NIH, Bethesda, USA). Comparable images and data are expressed as the ratio (%) of osteoclast surface/bone surface. Data are shown as mean ± SEM.