The peroxisome numerical abundance increased during osteoblast differentiation.

(A) In primary osteoblast cultures (day 12) from the calvariae of newborn mice, more than 95% of the cells were positively stained for the early osteoblast marker OPN. (B) The formation of calcium nodules increased in primary osteoblasts during culture as shown by Alizarin red staining of the Petri dishes. (C-L) Immunofluorescence stainings of osteoblasts at different time points during culture detecting cell proliferation using anti-Ki67 antibodies (C-G) and peroxisome numerical abundance using anti-PEX14 antibodies (H-L). Nuclei were visualized with Hoechst 33342 (Hoechst, C-F). Representative images (C-F, H-K) and quantitative analysis (G, L) are shown.