The bone matrix adjacent to lacunae and canaliculi

Three techniques, phase contrast microscopy, microradiography, and electron microscopy, have been used to study the variation in mineralization and presence of collagen fibers in the bone matrix adjacent to lacunae and canaliculi. Undecalcified, partially decalcified and fully decalcified sections of normal bone from old individuals have been studied. No stains were used. A fairly good correlation of the results obtained with these techniques could be demonstrated as far as the degree of mineralization is concerned. A zone of modified matrix is found adjacent to lacunae and canaliculi and this zone is prone to hypermineralization. In certain areas, especially in interstitial bone, lacunae may become completely obliterated with a hypermineralized material. Collagen fibers are found at the surface of the lumen of lacunae and canaliculi. The arrangement of these fibers is in most cases different from that in the adjoining bone matrix producing a well delimited zone which separates the lacunae and canaliculi from the rest of the matrix. Microradiography of bone sections partially decalcified in EDTA indicates that decalcification in vitro may result in an initial preferential decalcification of areas previously hypercalcified.