Differences in the kinetics of the mineralization process in endochondral and intramembranous osteogenesis in human...

About 300 samples of bone tissue from femoral diaphyses and from parietal bones of calvaria were collected from human fetuses aged from 6-8 to 40-41 weeks in order to compare the kinetics of the mineralization process in endochondral and intramembranous bone formation. The crystallinity of bone mineral was evaluated by the method based on electron spin resonance (ESR) spectrometry, and mineral content was measured after ashing of the samples. Highly significant differences in the kinetics of deposition of mineral (ash content) and maturation of deposited mineral (crystallinity coefficient) were found between parietal bones and femoral diaphyses in the course of fetal development. In the early stages of development (6-8 to 10-12 weeks), the content of mineral and its crystallinity in parietal bones were significantly lower than in femoral diaphyses. In the parietal bones a gradual increase in both values was observed until they reached a plateau at the age of 30 weeks. On the other hand, in femoral diaphyses of 6-8-week-old fetuses mineral content was high and deposited mineral showed a high degree of crystallinity. Both these values did not change significantly until birth. The differences in kinetics of the mineralization process between the weight-bearing bones and bones that are not exposed to the influence of strong external forces are most probably genetically conditioned. The collected data supply embryological information and might be used in the future for evaluation of pathologic changes in skeletal development.