| The experimental Study of Osteoporotic Model Femal Rats Induced by Retinoic Acid on Bone histomorphometry Bone mineral density and Bone mechanicsWith the aim of studying the changes in histomorphometry, mineral density and mechanical properties of bone in rats induced by retinoic acid, the author tried to find but the mechanism of the changes in rat's bone. Thirty female Wistar rats,three to five months old, weighting 240-300g, were randomly divided into the normal group and osteoporotic model group. The rats of the latter were treated with retinoic acid 75mg./kg.d by stomach for 15 days to induce osteoporosis .the former was given the same volume of boiling water.all of rats were sacrificed by dislocating cervical at the end of the 15th day, Lumbars, femurs and tibias were taken out for experiment, measuriedthe changes in histopathology, mineral density and mechanical properties of bone,the characteristic change of osteoporosis was found out. Compared with the control rats, the cancellous and compact bone volume of the model rats were reduced markedly. The bone tissue microstructure showed some obvious pathological changes that the trabecular free end numbers were increased,the separation of trabecular and medulla ossium cavity became large, the thickness of trabecular and cortex of bone were decreased.Osteoclast was activated and multiplied clearly.At the same time it was found that bone mineral density was dropping .The results of lumbar compressing tests and femur three-point bending tests showed that loading,Young's modules and resorption energy of cortical bone and spongy bone in the model rats were less than those of the normal rats. |
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