卵巣摘出ラットにおける上顎骨, 下顎頭および大腿骨の構造変化に関する比較組織学的研究

抄録

Postmenopausal estrogen deficiency results in bone loss (osteoporosis) in humans and experimental animals. The acute and significant loss of trabecular bone in the ovariectomized (OVX) rat provides a useful experimental model of postmenopausal osteoporosis. Five months after ovariectomy of 3-month-old female rats, the mid and distal femurs, maxillae, and mandibular condyles were dissected and processed for light and backscattered electron microscopic examinations. Net trabecular bone values of femurs in OVX ats showed significant loss of trabecular (but not cortical) bones compared to those in sham-operated controls. Net bone volume in the maxillae of OVX rats was similar to that of controls. In mandibular condyles, OVX caused prominent bone loss similar to that in femurs. Throughout the observations, active osteoclastic bone resorption was rarely recognized, presumably due to the fact that the rats had been in the statistic post-OVX phase. These results suggested that, in this animal model of postmenopausal steoporosis, the bone loss is more prominent in trabecular bone areas formed by endochondral ossification such asmetaphyses of femurs and mandibular condyles than cortical bone areas formed by intramembranous ossification such as mid-diaphyses of femurs and maxillae.