Effects of Ovariectomy and Anatomical Position on the Compact Bone As Seen In Three MonthSummer Ovine Model Bryan KraftThe purpose of this study is to characterize the compact-bone remodeling response to an ovariectomy model of human postmenopausal osteoporosis. Animal models are a beneficial practice allowing for the evaluation of the effectiveness of medical therapies and devices on diseases. The ovine model was chosen for this study due to its large size, similar bone remodeling to humans, and cost Osteons per mm 2 , and the mean osteon area. Densitometry analysis was also performed using the microradiographs using image analysis and the use of an aluminum step wedge on each microradiograph as a key. Once all of the data was collected a 2-way repeated measures ANOVA statistical analysis was performed on the histomorphometry and densitometry data to evaluate the possible differences seen due to treatment, anatomical sector, and possible interaction of both. For the histomorphometry portion there was a significant variation seen between the caudal sectors of bone in the OVX vs control sheep in both the fraction of remodeled material and the mean osteonal area. There was also a significant variation seen between the caudomedial sectors of bone in the OVX vs control sheep for the average Osteons per mm 2 . For the densitometry analysis it was found that the OVX sheep had significantly lower bone density than the control sheep. This study shows that there are significant changes seen even after only 3 months with depleted estrogen levels and that differences can be seen based on the anatomical sector of the bone. With this information it will be important to take this into consideration when creating future studies using the ovariectomized ewe as an animal model for postmenopausal osteoporosis study.vi ACKNOWLEDGMENTS