The topographical distribution of radiocalcium in fresh untreated autografts and devitalized implants was compared with that in normal rat metatarsals by means of autoradiographs of undecalcified thin sections.
Ca45 was distributed in a disseminated fashion over the entire cortex, metaphysis, and epiphysis, with concentrations in the subendosteal zone in the normal metatarsals and fresh transplants, and in the subperiosteal zone in the devitalized implants.
In the epiphyseal plate, almost the entire hypertrophic cartilage zone was labeled, a finding at variance with the distribution of calcification demonstrated by staining procedures.
On a cellular level, concentrations of Ca45 were observed in and around osteocytes and their lacunae. The possible significance of these findings in relation to calcium metabolism is discussed.
Osteocyte remnants in the devitalized metatarsals also took up and concentrated radiocalcium.
On the basis of radioisotope uptake, the only significant morphological difference between living and devitalized bone was in the subendosteal and subperiosteal accumulation of radioisotope.