Quantitative investigation on osteocyte canaliculi in human compact and spongy bone.

By means of the two techniques (reflected polarized light and SEM) used in previous investigations (Remaggi et al., Calcif. Tissue Int., suppl. 3b, 26, 1983), the number of canaliculi departing from osteocyte lacunae was counted in compact and spongy bone of human tibiae from normal subjects of different ages.The statistical analysis of the results indicates that in both compacta and spongiosa the extension of the canalicular network is significantly greater in woven than in lamellar bone. In the latter, moreover, the number of canaliculi per unit lacunar surface appears to be proportional to the size of the lacunae and greater in lacunar walls facing the vascular source than in the opposite walls facing the cement line. This occurs in secondary osteons and in fragments of spongy trabeculae outlined by reversal lines.These results strongly suggest the hypothesis that the metabolic activity of the osteocytes differs according to the type of bone tissue and in different skeletal regions.