Abstract: AIM: To observe the changes of different parts of bones in rats 90 days after ovariectomized (OVX).METHODS: Twenty 4. 5-month-old virgin female Sprague-Dawley rats were randomly divided into 2 groups: sham group and OVX group. Rats in sham group were sham-operated, while rats in OVX group were bilaterally OVX. Rats in two groups were treated with 5 ml·kg^-1·d^-1 ethanol for 90 days. Parameters of the proximal tibial metaphysis (PTM), tibial shaft (Tx) and the fifth lumbar vertebral body (LVB) were analyzed by bone histomorphometry method.RESULTS: %Tb. Ar and Tb. N were decreased by 80. 5 % and 76. 1 %, Tb. Sp and Oc. N were increased by 468. 0 % and 356. 6 %, and MAR and BFR BV were increased by 43. 9 % and 95. 9 %, respectively, in PTM. The changes in LVB were not remarkable as those in PTM. %Tb. Ar and Tb. Th were decreased by 35. 0 % and 31. 0 %, while Oc. N and BFR BV were increased by 106. 9 % and 126. 8 %, respectively. The cortical bone and marrow areas of tibial shaft did not change in Tx, but bone formation parameters (%P-LPm, %E-LPm ) were increased.CONCLUSION: After OVX for 90 days, high bone turnover osteopenia model is duplicated successfully in rats. Different parts of the bones have different reaction to ovariectomization in rats.

Key words: osteoporosis, bone histomorphometry, ovariectomized rats, cancellous bone, cortical bone