Structure of the osteocyte capsule in rats with hypervitaminosis-D and rickets

A histochemical and topo-optical study was made of the changes of the osteocyte capsule (OC) of the cortical and spongious bone layers of the tibia and vertebra of rats with hypervitaminosis-D and rickets. In hypervitaminosis-D the number of stained OCs was found to decrease. After treatment with high doses of vitamin D, a broadening of the OCs was noted in the area of demineralizing bone. Under the polarization microscope a decrease occurred in the proportion of birefringent OCs, more marked in birefringence than in staining. Since bone demineralization due to vitamin D was not followed by a rise in the number of osteoclasts, it is concluded that osteocytic activity has an important role in demineralization as shown by the broadened OC. In rachitic rats considerably fewer OC took the stain and showed birefringence than in the controls. Thus, alteration of the OC structure disturbs the nutrition of bone tissue and thereby aggravates the pathological process.