Adaptations in the Mandible and Appendicular Skeleton of High and Low Bone Density Inbred Mice

Abstract

The appendicular skeletons of high [C3H/HeJ (C3H)] and low [C57BL/6J (B6)] density inbred mice have been shown to differ in morphology, mechanical properties, and cellular activity. The focus of the current study was to (1) characterize the mandibular bone formation rate (BFR/BS), bone mass, indentation modulus (IM), and hardness of C3H and B6 mice and (2) investigate the relationship of the mechanical properties in three skeletal sites: mandible, femur, and tibia. Specimens from 17-week-old female C3H and B6 (n = 15/group) mice were obtained. Mandibular bone mass was estimated from the lateral-view area (LVA) and transverse cross sections. BFR/BS was measured in the mandibular section distal to the third molar. In addition, bone blocks from the distal surface of the third molar and the femoral and tibial midshaft were obtained for mechanical testing. BFR/BS, cortical area, and LVA were greater (P < 0.001) in C3H mandibles. IM was approximately 2 GPa higher in the C3H mandible (P > 0.05), femur (P < 0.001), and tibia (P < 0.01). Mandibular IM was lower (P < 0.05) than the femoral and tibial IM within each inbred mouse. IM was not significant between C3H and B6 mandibles. However, the magnitude of the difference ( approximately 12%) in the mandible was similar to the difference in the appendicular skeleton. This mandibular bone phenotype is similar to that observed in the appendicular skeleton of these distinct inbred mice.

Postpubertal Architectural Developmental Patterns Differ Between the L3 Vertebra and Proximal Tibia in Three Inbred Strains of Mice

“…TMD provides a more direct understanding of mineralization but has rarely been reported. Recently, bone mineralization was shown to proceed rapidly in postnatal BALB/cByJ mice, with TMD reaching 51% of mature values at 1 day of age and 80% by 40 days. Variation in TMD across anatomic sites has not been examined, but BMD is clearly site specific. Despite these limitations, timing of peak BMD measured by Beamer et al is commonly adopted as an indicator of skeletal maturity.…”

“…(1,15) Despite these limitations, timing of peak BMD measured by Beamer et al (1) is commonly adopted as an indicator of skeletal maturity. (2,3,10,(16)(17)(18)(19) Developmental patterns of bone structure have primarily focused on the cortex (9,10,12) or the trabecular compartment of C57BL/6J mice. (11,20) Architectural parameters have been found to peak early and at different times for the cortical and trabecular compartments.…”

Alveolar Process Anabolic Activity in C3H/HeJ and C57BL/6J Inbred Mice

“…The appendicular skeleton of C3H and B6 inbred mice has been well characterized 7–10 . The C3H skeleton demonstrates greater bone mineral density, indentation modulus, BFR/BS, and bone mass than the B6 skeleton 7,10 . The bone response to mechanical loading is greater in the B6 appendicular skeleton compared to the C3H skeleton 8 .…”

Oncologic doses of zoledronic acid induce site specific suppression of bone modelling in rice rats

“…Sections from the proximal tibial metaphyses were also selected for histomorphometric analyzes. The method has been described previously . The following histomorphometric parameters were calculated as follows: mineral apposition rate (MAR, μm/d), mineralizing surface/bone surface (MS/BS) and bone formation rate/bone surface (BFR/BS, μm 3 /μm 2 /d) …”