The absence of the CT/CGRP gene is protective against estrogen deficiency–mediated bone loss. At 3 months, WT and KO female mice received ovariectomy or a sham procedure. Animals were sacrificed at age 5 months following dual calcein labeling. (a) Histologic analysis of the vertebrae of WT and KO animals after ovariectomy or a sham procedure (see Methods). (b) Static histomorphometric analysis of vertebral bodies from WT (gray bars) and KO (black bars) mice. Graphs provide data for trabecular bone volume as a ratio of total bone volume (BV/TV) and trabecular number (TbN). Significant differences were observed between WT sham and WT OVX animals (**P < 0.01), and between WT and KO animals in both groups (*P < 0.05). (c) Histomorphometric analysis of osteoclast number and osteoblast number per mm bone perimeter. (d) Dynamic histomorphometric analysis of bone formation rate per bone surface in WT and KO mice after ovariectomy or a sham procedure. (e) Biomechanical properties of femora after ovariectomy or a sham procedure. Ovariectomy resulted in decreased force needed to break bone as determined by a three-point bending test (*P < 0.05). All experiments included five animals per group; bars represent mean ± SD.