Fig. 5. Bone characteristics of Gja1^Jrt/+ mice. (A) Dual energy x-ray absorptiometry (PIXImus) to measure bone mineral content (BMC), bone area and bone mineral density (BMD) of femurs (males; 22 weeks) showed that BMC and BMD were significantly lower in Gja1^Jrt/+ x FVB mice compared with wild-type littermates (+/+). (B) The distal metaphysis of the left femurs were scanned by micro-CT. Two-dimensional images were used to generate 3D reconstructions that clearly showed reduced trabeculae and thin cortices in Gja1^Jrt/+ mice compared with wild-type littermates (+/+) at 12 weeks and 6 weeks (data not shown). Morphometric parameters, including percent bone, trabecular thickness distribution, trabecular connectivity, structure model index and cortical thickness, calculated with 3D Creator software supplied with the instrument confirmed the osteopenia in Gja1^Jrt/+ animals (not shown). (C) Hematoxylin and Eosin-stained paraffin sections of distal femurs in control (+/+) and in Gja1^Jrt/+ mice. A reduction in bone trabeculae was seen as early as 8 weeks of age in the Gja1^Jrt/+ mice versus the control mice (i), and progressive bone marrow atrophy was observed in Gja1^Jrt/+ mice at 17-18 weeks (ii) and 25 weeks (iii). With aging, the bone marrow space was almost completely atrophied in 51 week Gja1^Jrt/+ mice versus the 62 week control (+/+) (iv).