For several rats, one trabecula was selected and analyzed as it developed this website over time after PTH

treatment. Figure 7 shows how PTH in this particular trabecula first led to filling and overfilling of cavities, while later, more bone was added to the surface of the trabecula resulting in a thicker trabecula. Also, resorption still appeared to take place in this trabecula. Another trabecula after segmentation of the image appeared cleaved due to OVX-induced increased resorption. PTH treatment led to bone formation, which took place where it was most beneficial, i.e., at the cleaved site, restoring the trabecula. This indicates that there see more probably was still a thin line of bone left in the center, which was unaccounted for after segmentation, but large enough for bone formation to take place. It was found that for all rats, the maximum trabecular thickness continued to increase over time. Therefore, no maximum limit for trabecular thickness appeared to be present. Fig. 7 A trabecula in two PTH-treated ovariectomized rats was tracked over time

to determine the development of bone formation (1 and 2). On the left of 1 and 2, you see three-dimensional segmented images of a trabecula, after PTH treatment is started at week 8, taken at weeks 8 (a), 10 (b), 12 (c), and ADP ribosylation factor 14 (d). On the right, you see overlaid two-dimensional segmented sections comparing weeks 8 and 10 (e), 10 and 12 (f), and 12 and 14 (g). Yellow indicates resorbed bone, green newly formed bone, and red unchanged bone. Bone formation is clearly seen over time in both trabeculae. In trabecula 1, bone is mostly deposited in the cavities in the first 2 weeks, while later on bone is added to the surface. In trabecula 2, the trabecula appears cleaved after segmentation, although most likely

there was still a thin line of bone present. PTH treatment leads to bone formation at the cleaved site, where it is most needed hereby restoring the trabecula Prediction of gain in bone mass after PTH treatment The linear correlations between several structural parameters and the gains in bone mass, gain in bone volume fraction, final bone mass, and final bone volume fraction after PTH treatment varied between the specific parameters as well as bone regions (Table 1). More significant predictions were found for the metaphysis than the epiphysis. Best correlations were found between BV and BV/TV at week 0 and BV and BV/TV at week 14, respectively, in both the meta- and epiphysis. Paradoxically, the loss of bone after OVX did not predict the gain of bone after PTH treatment well. From structural parameters evaluated at week 8, bone surface (BS) was the best predictor of the gain in bone after PTH.