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F Remaggi

Publications and source records attributed to F Remaggi.

12 recordsLinked to original sources
PubMed1998

Morphometric investigation on osteocytes in human auditory ossicles.

An osteocyte lacunae differential count (1-lacunae with live osteocytes, 2-lacunae with degenerating osteocytes, 3-empty lacunae) was carried out on ear ossicles and clavicles from cadavers as well as on stapes removed by stapedotomy. The distance of the three types of lacunae from the vascular source was also determined by a computer-assisted light microscope. Results showed that the delayed fixation of bone from cadavers does not significantly interfere with osteocyte preservation, at least with the scope of this investigation. The results of osteocyte differential count show that the number of empty lacunae and lacunae with degenerating osteocytes: (a) is significantly higher in ear ossicles than in clavicles, (b) increases with age, (c) is higher in stapes than in incuses and mallei, (d) increases with the distance from the vascular sources in both ear ossicles and clavicles. Additionally it appeared that the process of osteocyte degeneration in ear ossicles is very rapid and widespread, over 40% of the cells being dead within the 2nd year of age. In the light of the recent literature and personal findings, which ascribe to osteocytes the function of mechanical detectors, and considering that bone remodeling occasionally occurs in ear ossicles, it is postulated that osteocyte death in these bones could be a programmed phenomenon (apoptosis?), due to which they lose the ability to react to strains and stresses and achieve the structural stability they need to perform their peculiar stereotyped function.

Adult↗
PubMed1996

Histomorphological and chemico-physical analyses of the mineral matrix of micropetrotic human bone.

Micropetrotic areas of human bone were analyzed with reference to their distance from blood vessels and to the age of the subjects. Undecalcified bone sections were treated with various solvent, soaking and etching substances to establish the nature of the material occluding the osteocytic canalicular cavities, and were examined by means of microradiographic and microdurimetric methods and X-ray microanalysis to evaluate the degree of mineralization in the bone matrix. Since it was only after strong etching with HCl that the canalicular network became visible under light and scanning electron microscopy, it is clear that the debris filling the canalicular network consists almost entirely of mineral substance. The degree of mineralization of micropetrotic bone is high because it is always a more mature type of bone, but the mineral content of the matrix and the Ca/P ratio do not differ significantly from those of neighbouring bone where the canalicular network is fully pervious.

Adult↗
PubMed1995

Quantitative evaluation on osteocyte canalicular density in human secondary osteons.

Osteocyte canalicular density (OCD) was evaluated at different levels of the wall of human secondary osteons, in subjects of different ages, to find out whether any correlation exists between the extension of the canalicular network and the exponential decrement of the appositional growth rate (AGR), which has been shown to occur during osteon formation. Scanning electron microscopy (SEM) was used to count the number of canalicular openings per unit surface on large Haversian canals of forming osteons as well as on small canals of completed osteons. Reflected polarized light microscopy (RPL) enabled the number per unit length of canaliculi to be counted at different concentric levels of the osteons. The results of both techniques agree in showing that, in the subjects examined, OCD does not change significantly throughout the osteon wall. Since no correlation exists between OCD and AGR, it follows that osteoblast flattening which was shown to occur in parallel to the decrement of the rate of concentric bone deposition, does not seem to depend primarily on the number of osteoblast-osteocyte contacts, but on other factors.

Adult↗
PubMed1982

Activity of osteoclasts and osteocytes in compact human bone at various ages, both with and without osteoporosis.

As part of a programme of research designed to assess the respective roles of osteoclasts and osteocytes in the processes of bone resorption, the metabolic activity of these cells was evaluated indirectly by a morphometric method in the compact bone of human tibias from subjects of various ages, both normal and those affected by osteoporosis. Statistical analysis of the quantitative data was in agreement with the microradiographic examination of the sections, and showed that whereas the intensity of osteoclastic resorption varied in the various subjects according to age, periosteocytic osteolysis--in the classical sense of a phenomenon involving widening of the lacunae detectable with the optical microscope--did not occur in compact bone whether it was normal or highly porotic.

Adult↗
PubMed1981

Morphometric analysis of osteoblast dynamics in the chick embryo tibia.

Structure and size of the osteoblasts have been analyzed during growth of the tibial diaphyses in chick embryos from 10 days incubation until hatching. Statistical analyses of the results indicate that both size and density of the osteoblasts gradually decrease from the subperiosteal towards the endosteal regions of the shaft; the osteoblast secretory territory, on the other hand increases. These structural changes of the osteoblasts, which appear to be related to differences of the appositional growth rate, seem to derive mainly from structural modifications of differentiated osteoblasts rather than from differentiation of new osteoblasts, of progressively smaller size, from osteoprogenitor cells. The data reported in this paper compared with those in previous investigations indicate that the size of the osteoblasts does not significantly differ in animals of different species.

Animals↗
PubMedDate not supplied

Histomorphometric study on the osteocyte lacuno-canalicular network in animals of different species. II. Parallel-fibered and lamellar bones.

The shape, size and density of osteocyte lacunae in parallel-fibered and lamellar bone were histomorphometrically analyzed in relation to the organization of the collagen fiber texture and the animal species (frog, sheep, dog, bovine, horse and man). The following parameters were measured under the light microscope (LM) by a computer-assisted image analyzer: 1) shape, size and distribution of osteocyte lacunae; 2) osteocyte lacuno-canalicular density. In close agreement with our previous studies, which includes woven bone, it resulted that in all animals (even in frog) osteocyte lacunae have a rounded globous shape in woven bone and an oval shape in both parallel-fibered and lamellar bone; in the latter, however, they are more flattened, only located in loose lamellae and thus regularly distributed in rows. Osteocyte lacunar density is higher in woven-fibered, intermediate in parallel-fibered and lower in lamellar bone, whereas no correlation seems to exist with the animal species. In conclusion, these results suggest that osteocyte shape, size and density seem to depend mainly on collagen fiber texture rather than on the animal species. The role of osteocyte-recruitment on the spatial organization of collagen fibers in bone tissues is discussed.

Animals↗
PubMedDate not supplied

Histomorphometric study on the osteocyte lacuno-canalicular network in animals of different species. I. Woven-fibered and parallel-fibered bones.

A comparative histomorphometric study was carried out on the extension of lacunocanalicular network in two types of bone tissue (woven and parallel-fibered) in shaft bones of various animals (Frog, Chicken, Rabbit, Bovine, Horse, Dog, Man), with the aim to understand whether the distribution of osteocyte network is related to the organization of the collagen fibers or to the animal species. By means of a light microscope (LM) connected with an image-Analyser the following parameters were measured: 1) the cross-sectional area and the volume of osteocyte lacunae; 2) the osteocyte density; 3) the number of canaliculi departing both from the whole outline of the sectional area of osteocyte lacunae and, in the parallel-fibered osteons only (both with LM and SEM), from their two opposite walls, i.e., from the wall facing the Haversian canal (vascular wall) and from that facing the cement line (peripheral wall). In all the animals studied the size and density of osteocyte lacunae as well as the extension of the canalicular network proved to be markedly higher in woven than in parallel-fibered bone, whereas no relation with the species was found. These findings suggest that the function of osteocyte is mainly involved in the regulation of skeletal homeostasis, as discussed in the present paper.

Animals↗