. Calcified tissues; proceedings. Bone; Collagen; Calcification. The Osteon Calcification as Revealed by the Electron Microscope 145 In contrast with the lamellae, the interlamellar cementing zones show only one feature, the calcified bands are missing or very rare. The crystallites have the same shape and about the same size, but they are irregularly distributed and orientated in all directions forming at some points whorled figures. In fully calcified osteons the lamellae show no appreciable qualitative differences from those of osteons in the initial stages of calcification (Fig. 4). Howeve
. Calcified tissues; proceedings. Bone; Collagen; Calcification. The Osteon Calcification as Revealed by the Electron Microscope 145 In contrast with the lamellae, the interlamellar cementing zones show only one feature, the calcified bands are missing or very rare. The crystallites have the same shape and about the same size, but they are irregularly distributed and orientated in all directions forming at some points whorled figures. In fully calcified osteons the lamellae show no appreciable qualitative differences from those of osteons in the initial stages of calcification (Fig. 4). However, compari-. ithin longitudinal sec of a fully calcified osteon. Expla son of micrographs from osteons both at the initial stage of calcification and from fully calcified ones suggests that the number of needle-shaped crystallites increases in the latter. The surfaces covered by elongated crystallites as well as those covered by calcified bands were measured in 56 micrographs. The results show that the areas covered by needle-shaped crystallites are predominant in the osteon in the initial stage of ossification and correspond to about 69 per cent. The same areas increase by 14 per cent, when osteons complete their ossification going up to 83 per cent. The statistical analysis shows that the differences between the two mean values are highly significant, t being for P = This value is only indicative. In order to obtain more reliable data on the actual increase of calcium it would be necessary to consider the spatial distribution, density and dimensions of the calcified material in the two types of apatite deposition as the cross-banding has a lower opacity to the electron beam than the other calcified areas. At the moment this problem presents difficulties which still have to be solved. In the fully calcified osteons the interlamellar cementing zones are formed almost entirely of needle-shaped crystallites, which makes it difficult to establish whether the calcium sa
Size: 1812px × 1379px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookcollectionbiodiversity, booksubjectbone
