Development of the micro architecture and mineralization of the basilar part of the pig occipital bone.

In this study, the development of the architecture and the degree and distribution of mineralization in the basilar part of the pig occipital bone, one of the contact points between the spine and skull base, was investigated. Multiple regions of the basiocciput of pig specimens of different gestational ages were examined with three-dimensional microcomputed tomography (microCT). The cortex of the basilar part developed from a structure with a large intertrabecular separation into a more compact one, whereas its center maintained a trabecular structure. The cortex displayed a significant increase in bone volume fraction with age, together with an increase in trabecular thickness. In the center no change in bone volume fraction was observed, because of a combined decrease in trabecular number and increase in trabecular separation. During development the degree of mineralization was almost identical in both the center and the cortex and it tended to increase with age. This chance was, however, insignificant. The distribution of mineralization within the trabecular elements of both regions demonstrated that the cores of the elements were more highly mineralized than their surfaces. This difference in mineralization confirms the preexisting notion that trabecular elements grow in size due to surface apposition of new bone that initially is less mineralized.