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GASTONE MAROTTI

Professore emerito
Dipartimento di Scienze Biomediche, Metaboliche e Neuroscienze sede Policlinico


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Pubblicazioni

2013 - The problem of bone lamellation: An attempt to explain different proposed models [Articolo su rivista]
Marotti, Gastone; Ferretti, Marzia; Palumbo, Carla
abstract

Collagen texture and osteocyte distribution were analyzed in human woven- and lamellar-bone using scanning and transmission electron microscopy. We provide data substantiating the concept that lamellar bone is made up of an alternation of dense-acellular lamellae and loose-cellular lamellae, all exhibiting an interwoven texture of collagen fibers. An attempt is also made to explain how the present findings might conform to those of authors whose models propose orderly, geometric arrangements of collagen fibers inside bony lamellae. Such a comparison is possible because the present investigation analyzes split loose lamellae and tangentially-sectioned dense lamellae. It emerged that only loose lamellae can be dissected, revealing a loose interwoven collagen texture and halved osteocyte lacunae. Dense lamellae cannot be split because of their compactness. The analysis of tangentially sectioned dense lamellae demonstrates that they consist of a network of interwoven collagen fiber bundles. Inside each bundle, collagen fibers run parallel to each other but change direction where they enter adjacent bundles, at angles as described by other authors whose TEM investigations were performed at a much higher magnification than those of the present study. Consequently, what these authors consider to be a lamella are, instead, bundles of collagen fibers inside a lamella. There is discussion of the role played by the manner of osteocyterecruitment in the deposition of lamellar- and wovenbone and how the presence of these cells is crucial for collagen spatial arrangement in bone tissues.


2010 - New aspects of Ferutinin effect in preventing osteoporosis [Abstract in Rivista]
Ferretti, Marzia; Cavani, Francesco; Bertoni, Laura; Zavatti, Manuela; Taronna, ANGELO PIO; Carnevale, Gianluca; Benelli, Augusta; Zanoli, Paola; Marotti, Gastone; Palumbo, Carla
abstract

The results of the study suggest that ferutinin role, in preventing osteoporosis due to estrogen deficiency, is expressed in inhibiting osteoclast erosion rather than in enhancing osteoblast deposition (as previously suggested); moreover, in all F-OVX groups the bone turnover is very low and seems correlated to the trivial body weight increase, which, in turn, depends on ferutinin treatment.


2010 - STATIC OSTEOGENESIS AND DYNAMIC OSTEOGENESIS: THEIR RELEVANCE IN DENTAL BONE IMPLANTS AND BIOMATERIAL OSSEOINTEGRATION [Articolo su rivista]
Marotti, Gastone; Zaffe, Davide; Ferretti, Marzia; Palumbo, Carla
abstract

The present report summarizes the results of a series of investigations carried out in our laboratory on intramembranous ossification occurring under normal condition during skeletal organogenesis and osseointegrations of dental implants and biomaterials. No morphological differences were observed between normal and pathological conditions, since the same following sequence of events were found. Inside the embryonic mesenchyme or the connective tissue formed after bleeding, due to surgery, cords of plum cells, displaying the typical osteoblastic structure, differentiate in between the blood capillaries. These osteoblasts appear to be stationary since they do not move, but transform into osteocytes in the same site where they differentiated, thus giving origin to a trabecular woven-bone framework laid down by static osteogenesis (SO). Soon after, typical movable osteoblastic laminae differentiate along the surface of this SO-trabeculae and thicken them with lamellar bone formed by dynamic osteogenesis (DO). SO seems to depend on inductive stimuli and appears to be mechanically independent, whereas DO mainly depend on mechanical strains. Additionally SO-bone is a bad quality bone because of its woven texture and high microporosity, due to the many osteocyte lacunae it contains, whereas DO-bone generally is a lamellar bone and thus mechanically much more resistant.The clinical implication of these findings, as regards the time of load application after prostheses/biomaterials implantation, is discussed.


2008 - Influence of ferutinin on bone mass and its side effects in ovariectomized rats. [Abstract in Rivista]
Ferretti, Marzia; Palumbo, Carla; Bretoni, L.; Cavani, Francesco; Resca, E.; Benincasa, Marta; Carnevale, Gianluca; Zavatti, Manuela; Montanari, C.; Benelli, A.; Zanoli, P.; Marotti, Gastone
abstract

Ferutinin seems to display the same effects on bone mass recorded with estradiol, but with respect to estrogens it seems to extert a protection against uterine carcinoma.


2008 - Ovariectomy sensitizes rat cortical bone to whole-body vibration [Articolo su rivista]
A., Rubinacci; M., Marenzana; Cavani, Francesco; F., Colasante; I., Villa; J., Willnecker; G. L., Moro; L. P., Spreafico; Ferretti, Marzia; F., Guidobono; Marotti, Gastone
abstract

This study was designed to determine the modulatory effect of estrogen on mechanical stimulation in bone. Trabecular and cortical bone compartments of ovariectomized rats exposed to whole-body vibration of different amplitudes were evaluated by peripheral quantitative computed tomographic (pQCT) analysis and histomorphometry and compared to controls not exposed to vibration. Rats underwent whole-body vibration (20 minutes/day, 5 days/week) on a vibration platform for 2 months. The control rats were placed on the platform without vibration for the same time. We divided rats into six groups: a sham control (SHAM); a sham vibrated (SHAM-V) at 30 Hz, 0.6 g; a SHAM-V at 30 Hz, 3g; an ovariectomized control (OVX); an ovariectomized vibrated (OVX-V) at 30 Hz, 0.6 g; and an OVX-V at 30 Hz, 3g. In vivo, pQCT analyses of the tibiae were performed at the start of the experiment and after 4 and 8 weeks. After 8 weeks the tibiae were excised for histomorphometric and for in vitro pQCT analyses. In the SHAM-V group, vibration had no effect upon the different bone parameters. In the OVX-V group, vibration induced a significant increase compared to the OVX group of the cortical and medullary areas (P < 0.01) and of the periosteal (P < 0.01) and endosteal (P < 0.05) perimeters at the 3 g vibration. The strain strength index increased in the OVX-V group significantly (P < 0.01) at the higher vibration. The results showed that low-amplitude, high-frequency whole-body vibration is anabolic to bone in OVX animals. The osteogenic potential is limited to the modeling of the bone cortex and depends on the amplitude of the vibration.


2007 - Phytoestrogen effects on bone mass in ovariectomized rats: preliminary histomorphometric analysis. [Abstract in Rivista]
Ferretti, Marzia; Palumbo, Carla; Cavani, Francesco; Bertoni, Laura; Resca, E.; Carnevale, Gianluca; Zavatti, Manuela; Montanari, C.; Benelli, A.; Zanoli, P.; Marotti, Gastone
abstract

Phytoestrogens ferutinine could prevent in rats the risk of osteoporosis in estrogen deficient conditions and it could enhance the recover of bone mass in osteoporotic OVX rats.


2007 - The mechanism of transduction of mechanical strains into biological signals at the bone cellular level [Articolo su rivista]
MAROTTI, Gastone; PALUMBO, Carla
abstract

As appears from the literature, the majority of bone researchers consider osteoblasts and osteoclasts the only very important bony cells. In the present report we provide evidence, based on personal morphofunctional investigations, that such a view is incorrect and misleading. Indeed osteoblasts and osteoclasts undoubtedly are the only bone forming and bone reabsorbing cells, but they are transient cells, thus they cannot be the first to be involved in sensing both mechanical and non-mechanical agents which control bone modeling and remodeling processes. Briefly, according to our view, osteoblasts and osteoclasts represent the arms of a worker; the actual operation center is constituted by the cells of the osteogenic lineage in the resting state. Such a resting phase is characterized by osteocytes, bone lining cells and stromal cells, all connected in a functional syncytium by gap junctions, which extends from the bone to the vessels. We named this syncytium the Bone Basic Cellular System (BBCS), because it represents the only permanent cellular background capable first of sensing mechanical strains and biochemical factors and then of triggering and driving both processes of bone formation and bone resorption. As shown by our studies, signalling throughout BBCS can occur by volume transmission (VT) and/or wiring transmission (WT). VT corresponds to the routes followed by soluble substances (hormones, cytokines etc.), whereas WT represents the diffusion of ionic currents along cytoplasmic processes in a neuron-like manner. It is likely that non-mechanical agents first affect stromal cells and diffuse by VT to reach the other cells of BBCS, whereas mechanical agents are first sensed by osteocytes and then issued throughout


2006 - Different skeletal regional response to continuous brain infusion of leptin in the rat. [Articolo su rivista]
F., Guidobono; F., Pagani; V., Sibila; C., Netti; N., Lattuada; D., Rapetti; E., Mrak; I., Villa; Cavani, Francesco; Bertoni, Laura; Palumbo, Carla; Ferretti, Marzia; Marotti, Gastone; A., Rubinacci
abstract

This study was designed to evaluate whether or not continuous intracerebroventricular infusion of leptin (1.5 mu g/rat/24 h, for 28 days) produced different regional response on the skeleton of growing rats. Leptin reduce the accretion of total femoral bone mineral content (BMC) and density (BMD). This effect was related to a reduction of metaphyseal femur as no changes were detected in the diaphysis. Despite the reduced accretion in the volumetric of both femur and tibia compared to controls, leptin had no significant effects on the lumbar vertebrae. Urine deoxypyrydincline and serum osteocalcin remained more elevated in the leptin-treated group as compared to controls. The results demonstrate that long-term central infusion of leptin activates bone remodeling with a negative balance. Leptin induces distinct responses in the different structure of bone and in the axial and appendicular skeleton. (c) 2005 Elsevier Inc. All rights reserved.


2006 - Does Static precede dynamic osteogenesis in endochondral ossification as occurs in intramembranous ossification? [Articolo su rivista]
Ferretti, Marzia; Palumbo, Carla; Bertoni, Laura; Cavani, Francesco; Marotti, Gastone
abstract

Endochondral ossification takes place with calcified cartilage cores providing a rigid scaffold for new bone formation. Intramembranous ossification begins in connective tissue and new bone formed by a process of static ossification (SO) followed by dynamic ossification (DO) as previously described. The aim of the present study was to determine if the process of endochondral ossification is similar to that of intramembranous ossification with both a static and a dynamic phase of osteogenesis. Endochondral ossification centers of the tibiae and humeri of newborn and young growing rabbits were studied by light and transmission electron microscopy. The observations clearly showed that in endochondral ossification, the calcified trabeculae appeared to be lined first by osteoclasts. The osteoclasts were then replaced by flattened cells (likely cells of the reversal phase) and finally by irregularly arranged osteoblastic laminae, typical of DO. This cellular sequence did not include osteoblasts seen in the phase of SO. These findings clearly support our working hypothesis that SO only forms in soft tissues to provide a rigid framework for DO, and that DO requires a rigid mineralized surface. The presence of osteocytes in contact with the calcified cartilage also suggests the existence of stationary osteoblasts in endochondral ossification. Stationary osteoblasts did not appear to be a unique feature of SO. The presence of stationary osteoblasts may appear to provide the initial osteocytes during osteogenesis that may function as mechanosensors throughout the bone tissue. If this is the case, then bone would be capable of sensing mechanical strains from its inception.


2006 - Preliminary observations on transplants of vascularized bone scaffolds: an experimental and morphological study. [Abstract in Rivista]
Ferretti, Marzia; Palumbo, Carla; Bertoni, Laura; Cavani, Francesco; Carbonara, A.; DE SANTIS, Giorgio; Marotti, Gastone
abstract

Bone formation occurring inside and around dead bone implanted scaffolds seems to follow the same sequence of events that are observed during normal intramembranous ossification.


2005 - Endochordral versus intramembranous ossification: analogies and differences. [Abstract in Rivista]
Ferretti, Marzia; Palumbo, Carla; Bertoni, Laura; Marotti, Gastone
abstract

Stationary osteoblasts are not a typical finding of static osteogenesis; they may also exist in the earòly stage of dynamic osteogenesis.


2004 - Endotendinous ossification and static osteogenesis: analogies and differences. [Abstract in Rivista]
Palazzini, S.; Palumbo, Carla; Ferretti, Marzia; Zaffe, Davide; Marotti, Gastone
abstract

In endotendinous ossification and in the early phase (SO) of intramembranous ossification the first trabecular framework fiorms in a different manner.


2004 - In vivo leptin expression in cartilage and bone cells of growing rats and adult humans [Articolo su rivista]
M., Morroni; R., De Matteis; Palumbo, Carla; Ferretti, Marzia; I., Villa; A., Rubinacci; S., Cinti; Marotti, Gastone
abstract

The present investigation was carried out to analyse, immunohistochemically, in vivo leptin expression in cartilage and bone cells, the latter restricted to the elements of the osteogenic system (stromal cells, osteoblasts, osteocytes, bone lining cells). Observations were performed on the first lumbar vertebra, tibia and femur of four rats and on the humerus, femur and acromion of four patients. Histological sections of paraffin-embedded bone samples were immunostained using antibody to leptin. The results showed that, in growing rat bone, leptin is expressed in chondrocytes and stromal cells, but not in osteoblasts; bone lining cells were not found in the microscopic fields examined. In adult human bone, leptin is expressed in chondrocytes, stromal cells and bone lining cells; osteoblasts were not found in the microscopic fields examined. Osteocytes were found to be leptin positive only occasionally and focally in both rat and human bone. The in vivo findings reported show, for the first time, that leptin appears to be expressed only in the cells of the osteogenic lineage (stromal cells, bone lining cells, osteocytes) that, with respect to osteoblasts, are permanent and inactive, i.e. in those cells that according to our terminology constitute the bone basic cellular system (BBCS). Because the BBCS seems to be primarily involved in sensing and integrating mechanical strains and biochemical factors and then in triggering and driving bone formation and/or bone resorption, it appears that leptin seems to be mainly involved in modulating the initial phases of bone modelling and remodelling processes.


2004 - Leptin expression in the cells of the osteogenic lineage of growing rat and adult human bones. [Abstract in Rivista]
Palumbo, Carla; Ferretti, Marzia; De Matteis, R.; Morroni, M.; Marotti, Gastone
abstract

Leptin seems to be involved in modulating the initial phases of bone modeling and remodeling processes.


2004 - Osteocyte dendrogenesis in static and dynamic bone formation: An ultrastructural study [Articolo su rivista]
Palumbo, Carla; Ferretti, Marzia; Marotti, Gastone
abstract

The present ultrastructural investigation into osteocyte dendrogenesis represents a continuation of a previous study (Ferretti et al., Anat. Embryol., 2002; 206:21-29), in which we pointed out that, during intramembranous ossification, the well-known dynamic bone formation (DBF), performed by migrating osteoblast laminae, is preceded by static bone formation (SBF), in which cords of stationary osteoblasts transform into osteocytes in the same site where they differentiated. The research was carried out on the perichondral center of ossification surrounding the mid shaft level of various long bones of chick embryos and newborn rabbits. Transmission electron microscope observations showed that the formation of osteocyte dendrites is quite different in the two types of osteogenesis, mainly depending on whether or not osteoblast movement occurs. In DBF, osteoblasts transform into small ovoidal/ellipsoidal osteocytes and their dentrites form in an asynchronous and asymmetrical manner in concomitance with, and depending on, the advancing mineralizing surface and the receding osteogenic laminae. In SBF, stationary osteoblasts give rise to big globous osteocytes, located inside confluent lacunae, with short and symmetrical dendrites that can radiate simultaneously all around their cell body because they are completely surrounded by unmineralized matrix. Contacts and gap junctions were observed between all osteocytes (both SBF- and DBF-derived) and between osteocytes and osteoblast's. Finally, a continuous osteocyte network extends throughout the bone, regardless of its static or dynamic origin. This network has the characteristic of a functional syncytium, potentially capable of modulating, by wiring transmission, the cells of the osteogenic lineage covering the bone surfaces. (C) 2004 Wiley-Liss, Inc.


2004 - Static and dynamic osteogenesis in bone regeneration and repair. [Abstract in Rivista]
Marotti, Gastone; Palumbo, Carla; Ferretti, Marzia; Cavani, Francesco; Botti, P.; Cadossi, Ruggero; Cane, V.
abstract

Static osteogenesis probably depends on inductive factors, whereas dynamic osteogenesis more likely is mailly conditioned by mechanical signals.


2002 - Apoptosis during static and dynamic bone formation. [Abstract in Rivista]
Palumbo, Carla; Ferretti, Marzia; DE POL, Anto; Marotti, Gastone
abstract

The study shows that apoptotic phenomena occur in cells of fibroblastic type, located between the newly-forming bony trabeculae and blood capillaries; however, the number of apoptotic cells is incomparably higher during dynamic bone formation than static bone formation.


2002 - Bone as an ionic exchange system: evidence for a link between mechanotransduction and metabolic needs [Articolo su rivista]
A., Rubinacci; M., Covini; C., Bisogni; I., Villa; M., Galli; Palumbo, Carla; Ferretti, Marzia; Muglia, Maria Antonietta; Marotti, Gastone
abstract

To detect whether the mutual interaction occurring between the osteocytes-bone lining cells system (OBLCS) and the bone extracellular fluid (BECF) is affected by load through a modification of the BECF-extracellular fluid (ECF; systemic extracellular fluid) gradient, mice metatarsal bones immersed in ECF were subjected ex vivo to a 2-min cyclic axial load of different amplitudes and frequencies. The electric (ionic) currents at the bone surface were measured by a vibrating probe after having exposed BECF to ECF through a transcortical hole. The application of different loads and different frequencies increased the ionic current in a dose-dependent manner. The postload current density subsequently decayed following an exponential pattern. Postload increment's amplitude and decay were dependent on bone viability. Dummy and static loads did not induce current density modifications. Because BECF is perturbed by loading, it is conceivable that OBLCS tends to restore BECF preload conditions by controlling ion fluxes at the bone-plasma interface to fulfill metabolic needs. Because the electric current reflects the integrated activity of OBLCS, its evaluation in transgenic mice engineered to possess genetic lesions in channels or matrix constituents could be helpful in the characterization of the mechanical and metabolic functions of bone.


2002 - Osteocyte dendrogenesis in static bone formation. [Abstract in Rivista]
Palumbo, Carla; Ferretti, Marzia; DE POL, Anto; Marotti, Gastone
abstract

All osteocytes, independently of their SBF or DBF origin, take part in the formation on the continuous osteocytic network, connected by electric synapsis (gap junctions), potentially capable of modulating by wiring transmission the cells covering the bone surfaces.


2002 - Static and dynamic osteogenesis: two different types of bone formation [Articolo su rivista]
Palumbo, Carla; Contri, Miranda; Marotti, Gastone; Ferretti, Marzia
abstract

The onset and development of intramembranous ossification centers in the cranial vault and around the shaft of long bones in five newborn rabbits and six chick embryos were studied by light (LM) and transmission electron microscopy (TEM). Two subsequent different types of bone formation were observed. We respectively named them static and dynamic osteogenesis, because the former is characterized by pluristratified cords of unexpectedly stationary osteoblasts, which differentiate at a fairly constant distance (28+/-0.4 mum) from the blood capillaries, and the latter by the well-known typical monostratified laminae of movable osteoblasts. No significant structural and ultrastructural differences were found between stationary and movable osteoblasts, all being polarized secretory cells joined by gap junctions. However, unlike in typical movable osteoblastic laminae, stationary osteoblasts inside the cords are irregularly arranged, variously polarized and transform into osteocytes, clustered within confluent lacunae, in the same place where they differentiate. Static osteogenesis is devoted to the building of the first trabecular bony frame-work having, with respect to the subsequent bone apposition by typical movable osteoblasts, the same supporting function as calcified trabeculae in endochondral ossification. In conclusion, it appears that while static osteogenesis increases the bone external size, dynamic osteogenesis is mainly involved in bone compaction, i.e., in filling primary haversian spaces with primary osteons.


2002 - The osteocyte-bone lining cell system as transducer of mechanical strains into biological signals. [Abstract in Rivista]
Rubinacci, A; Covini, M; Bisogni, C; Villa, I; Palumbo, Carla; Ferretti, Marzia; Marotti, Gastone
abstract

The study shows that OBLCS tends to restore BECF preload conditions by controlling ion fluxes at the bone-plasma interface, thus playing a pivotal role in mechano-transduction and mineral homeostasis.


2001 - Osteocyte-bone lining cell system responds to cyclic loading in a dose dependent manner [Abstract in Rivista]
Rubinacci, A.; Covini, M.; Bisogni, C.; Villa, I.; Galli, M.; Palumbo, Carla; Ferretti, Marzia; Ardizzoni, Andrea; Marotti, Gastone
abstract

The mutual interaction between osteocyte-bone lining cell system (OBLCS) and the surrounding bone extracellular fluid which feels the continuous network of lacuno-canalicular microcavities plays a role in mechanotransduction. The study shows that OBLCS responds to cyclic loading depending on the applied loading parameters in a dose- dependent manner.


2001 - Osteocyte-osteoclast morphological relationships and the putative role of osteocyte in bone remodeling [Articolo su rivista]
Palumbo, Carla; Ferretti, Marzia; A., Ardizzoni; Zaffe, Davide; Marotti, Gastone
abstract

An osteocyte lacunae differential count under the light microscope (LM) (1-lacunae with live osteocytes, 2-empty lacunae and lacunae with degenerating osteocytes) was carried out outside the reversal lines of osteonic lamellar bone from various mammals and man to evaluate the possibility of osteocyte survival where osteoclast resorption had occurred. The polarized light microscope (PLM) was used to establish the curvature of bony lamellae outside the convexity of reversal lines: concave lamellae indicate osteocytes reabsorbed on their vascular side where they radiate long vascular dendrites; convex lamellae indicate bone resorption on the osteocyte mineral side, radiating short dendrites. In all samples it was found that: a) about 60% of osteocytes outside the reversal lines were live; b) the percentage of alive osteocytes close to reversal lines is higher when they are attacked on their mineral side. The present data support our view that surviving osteocytes, particularly those attacked from their mineral side, might intervene in the final phase of bone resorption (osteoclast inhibition?). The fact that under the transmission electron microscope (TEM) intercellular contacts were never observed between osteocytes and osteoclasts indicates that if a modulation should occur between these two cellular types it could take place by a paracrine route only. The putative role of the cells of the osteogenic system, particularly osteocytes, in the bone remodeling cycle is also discussed.


2001 - Osteocyte-osteoclast morphological relationships and the putative role of osteocytes in bone remodeling. [Articolo su rivista]
Palumbo, Carla; Ferretti, Marzia; Ardizzoni, Andrea; Zaffe, Davide; Marotti, Gastone
abstract

An osteocyte lacunae differential count under the light microscope (LM) (1-lacunae with live osteocytes, 2-empty lacunae and lacunae with degenerating osteocytes) was carried out outside the reversal lines of osteonic lamellar bone from various mammals and man to evaluate the possibility of osteocyte survival where osteoclast resorption had occurred. The polarized light microscope (PLM) was used to establish the curvature of bony lamellae outside the convexity of reversal lines: concave lamellae indicate osteocytes reabsorbed on their vascular side where they radiate long vascular dendrites; convex lamellae indicate bone resorption on the osteocyte mineral side, radiating short dendrites. In all samples it was found that: a) about 60\% of osteocytes outside the reversal lines were live; b) the percentage of alive osteocytes close to reversal lines is higher when they are attacked on their mineral side. The present data support our view that surviving osteocytes, particularly those attacked from their mineral side, might intervene in the final phase of bone resorption (osteoclast inhibition?). The fact that under the transmission electron microscope (TEM) intercellular contacts were never observed between osteocytes and osteoclasts indicates that if a modulation should occur between these two cellular types it could take place by a paracrine route only. The putative role of the cells of the osteogenic system, particularly osteocytes, in the bone remodeling cycle is also discussed.


2000 - Do osteocytes intervene in regulating osteoclast activity?. [Abstract in Rivista]
Palumbo, Carla; Ferretti, Marzia; Zaffe, Davide; Marotti, Gastone
abstract

Osteocyte could intervene in the process of bone resorption.


1999 - Osteocyte-osteoclast morphological and putative functional relationships [Abstract in Rivista]
Palumbo, Carla; Ferretti, Marzia; Zaffe, Davide; Marotti, Gastone
abstract

Osteocytes could intervene in the process of bone resorption.


1999 - Static and dynamic bone formation and the mechanism of collagen fiber orientation. [Abstract in Rivista]
Marotti, Gastone; Ferretti, Marzia; Palumbo, Carla; Benincasa, Marta
abstract

Woven bone forms by FBS, whereas the deposition of a bone tissue with orderly arranged collagen fibers (parallel-fibered and lamellar bone) may only occur by DBF, i.e. by movable osteoblasts.


1998 - Morphometric investigation on osteocytes in human auditory ossicles [Articolo su rivista]
Marotti, Gastone; D., Farneti; Remaggi, Francesca; F., Tartari
abstract

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.


1998 - Osteocyte-bone lining cell system at the origin of steady ionic current in damaged anphibian bone. [Articolo su rivista]
A., Rubinacci; I., Villa; F. D., Benelli; E., Borgo; Ferretti, Marzia; Palumbo, Carla; Marotti, Gastone
abstract

A wound-generated steady electric current was measured by a two-dimensional vibrating probe system in the metatarsal banes of 22 adult frogs (Xenopus laevis) placed in amphibian Ringer. Inward currents were recorded entering a micrometric hole drilled through the cortex at middiaphyseal level. These steady state currents (mean +/- SD 8.50 +/- 2.77 mu A/cm(2)) last approximately 2 hours, were dependent on the presence of sodium in the incubation medium, were no more detectable after fixation, and were reduced to background level when the cell membranes were solubilized. These results agree with previous recordings of metatarsal bones of weanling mice, under identical conditions. Both results suggest that the measured ionic currents have a cellular origin. Metatarsal bones of adult amphibian were purposely selected for this study because, unlike mammalian bones, their shafts are avascular and only contain an osteocyte-bone lining fell system, as documented by scanning and transmission electron observations. Thus, unlike the data from previous investigations on mammals, the results succeeded in giving the first convincing evidence that the osteocyte-bone lining cell system is the origin of damage-generated ionic currents. As damage exposes bone ionic compartment to plasma, damage-generated ionic currents are representative of ion fluxes at bone plasma interface, and cells at the origin of the current generate the driving force of such fluxes. By demonstrating that osteocytes and bone lining cells are at the origin of the current, this study suggests that the osteocyte-bone lining cell system, though operating as a cellular membrane partition, regulates ionic flow between bone and plasma. Since strain-related adaptive remodeling could also depend on ionic characteristics and flow of the bone fluid through the osteocyte lacuno-canalicular network, the results reported here support the view that osteocyte and bone lining cells may constitute a functional syncytium involved in mineral homeostasis as well as in bone adaptation to mechanical loading.


1998 - Stromal cell structure and relationships in perimedullary spaces of chick embryo shaft bones [Articolo su rivista]
S., Palazzini; Palumbo, Carla; Ferretti, Marzia; Marotti, Gastone
abstract

Structure and relationships of stromal cells were studied by light (LM) and transmission electron microscopy (TEM) in the perimedullary spaces that form the growing cortex of the chick embryo tibia. Observation under LM showed that in all perimedullary spaces the interstices between the cells carpeting the bone surface and the endothelial Lining contain stromal cells surrounded by an amorphous matrix. Two types of stromal cells were distinguished: stellate and spindle-shaped. All stromal cells are alkaline phosphatase-positive. TEM showed that both types of stromal cells have cytoplasmic processes of Various length and calibre, coming into contact with each other as well as with endothelial. cells and osteoblasts or bone lining cells. Capillaries were found to have a continuous endothelial lining; occasionally endothelial cells radiate cytoplasmic processes towards stromal cells. Along all the above-mentioned cellular contacts adherens and/or gap junctions were often observed. The results of the present study, together with our previous findings on osteoblast-osteocyte relationships, show that the cells of the osteogenic lineage form a continuous protoplasmic network that extends from the osteocytes to the vascular endothelium, passing through osteoblasts (or bone lining cells) and stromal cells. The occurrence of gap junctions among this cytoplasmic network, namely of junctions enabling metabolic and electric coupling, indicates that it forms a functional syncytium, suggesting the hypothesis that the activity of the cells pertaining to the osteogenic Lineage might be regulated not only by diffusion (volume transmission) through the intercellular fluids of systemic (hormones) and local factors (cytokines, etc.) but also by signals issued through the cytoplasmic network of the osteogenic cells (wiring transmission).


1995 - Collagen texture and osteocyte distribution in lamellar bone. [Articolo su rivista]
Marotti, Gastone; Muglia, Ma; Palumbo, Carla
abstract

The osteocyte lacunae are only located inside loose lamellae.


1995 - Quantitative evaluation on osteocyte canalicular density in human secondary osteons. [Articolo su rivista]
Marotti, Gastone; Ferretti, Marzia; Remaggi, Francesca; Palumbo, Carla
abstract

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.


1994 - Histomorphological analysis of the effect of rigid fixation on growing sutures in the rabbit [Articolo su rivista]
A., Carinci; Zaffe, Davide; A., Pagliarini; L., Clauser; G., Calura; Marotti, Gastone; C., Curioni
abstract

The effect of internal rigid fixation (IRF) on bone growth was studied in an experimental model set up in the rabbit. The frontonasal suture of the right side was surgically bridged by a microplate. As reference for bone growth, four screws were placed symmetrically in the four bony segments including the frontonasal suture on both sides. The suture development was followed dynamically for 40 days on the basis of the position of the screws established radiographically. The rate of bone formation along the sutural bones was evaluated by means of the tetracycline labelling technique. The structure of the newly formed bone and its degree of mineralization were respectively analysed under polarized light and with microradiography. It was demonstrated that IRF prevents growth of the sutural membrane but not of the osteogenic process; as a consequence the constrained sutures soon undergo synostosis. This fact must be taken into consideration when IRF is employed in children in order to avoid delayed removal of the plate irreversibly stopping the growth of the constrained suture.


1994 - Structure and function of lamellar bone. [Articolo su rivista]
Marotti, Gastone; Muglia, Maria Antonietta; Palumbo, Carla
abstract

A comparative scanning and transmission electro microscopy study was carried out on human compact lamellar bone. The results obtained fully confirm our previous findings which show that bony lamellae are not made up of parallel-arranged collagen fibers, as classically maintasined.


1994 - The microscopic determinants of bone mechanical properties [Articolo su rivista]
Marotti, Gastone; Muglia, Maria Antonietta; Palumbo, Carla; Zaffe, Davide
abstract

Composition and structure of the bone matrix, i.e. the bony substance surrounding osteocyte microcavities, was considered in the Light of their mechanical implications. A novel classification of bone tissues was proposed, on the basis of recent comparative studies on collagen fiber texture and osteocyte lacunae distribution, performed under polarized light, scanning and transmission electron microscopies. In particular, contrary to the classical view, lamellar bone can no longer be considered a variety of parallel-fibred bone since bony lamellae are not made up of parallely arranged collagen fibers, but of highly interlaced fibers, the lamellation being due to the alternation of acellular collagen-rich and cellular collagen-poor layers, namely of dense and loose lamellae, respectively. It is postulated that the deposition of woven- and lamellar-bone depends on the manner of recruitment of the osteocyte-differentiating osteoblasts from the osteogenic laminae and not on the spatial orientation by osteoblasts of collagen fibers. The possible role played by osteocyte as mechanical sensor in selecting the type of bone tissue laid down on bone surfaces is discussed.


1992 - A quantitative evaluation of osteoblast-osteocyte relationships on growing endosteal surface of rabbit tibiae. [Articolo su rivista]
Marotti, Gastone; Ferretti, Marzia; Muglia, Maria Antonietta; Palumbo, Carla; S., Palazzini
abstract

Scanning electron microscopy (SEM) was used to quantify the intercellular relationships between osteoblasts and osteocytes on the growing endosteal surfaces of the medullary canal of the tibia in four rabbits of different ages. The area of each osteoblast was measured on the SEM micrographs by means of an Image Analyzer. The number of osteocyte cytoplasmic processes was indirectly evaluated by counting the canalicular openings present on the same microscopic fields after the removal of the osteoblasts. The metabolic activity of the osteoblasts was indirectly evaluated from their shape, and the structure was analyzed by transmission electron microscope (TEM) in sections taken from the samples studied by SEM. In all four animals, the surface area of the osteoblasts (OA) was found to vary a great deal, whereas the density of canalicular openings was fairly uniform. Moreover, although the OA mean value increases significantly with the age of the animals, the density of canalicular openings does not; it would therefore appear that the older the animal and the more flattened the osteoblasts, the greater the number of canaliculi beneath them. Since osteoblast activity has previously been shown to be inversely proportional to the area of the protoplasm in contact with the bone surface, it appears that the less active osteoblasts should contact a greater number of osteocyte cytoplasmic processes. These findings suggest that osteocytes might play an important role in modulating osteoblast activity and in recruiting osteoblasts that differentiate into osteocytes, possibly by means of inhibitory signals transmitted via gap junctions.


1992 - Quantitative aspects on osteoblast-osteocyte relationships. [Articolo su rivista]
Marotti, Gastone; Ferretti, Marzia; Muglia, M. A.; Palumbo, Carla
abstract

Osteocytes could modulate osteoblast activity by issuing inhibitory signals.


1991 - A SEM quantitative-study of osteoblast-osteocyte relationships on endosteal surface of growing rabbits. [Abstract in Rivista]
Marotti, Gastone; Ferretti, Marzia; Muglia, M. A.; Palumbo, Carla
abstract

The less active osteoblasts contact a greater number of osteocyte cytoplasmic processes. This fact suggest the hypothesis that osteocytes might exert an inhibitory effect on the secretory activity of osteoblasts.


1991 - Asymmetry of dendrites and alKaline phosphatase activity in preosteocytes and osteocytes of rabbit osteonic bone. [Abstract in Rivista]
Marotti, Gastone; Palumbo, Carla; Palazzini, S.; Farneti, D.
abstract

Alkaline phosphatase activity in preosteocytes seem to progress in parallel with the asymmetry of their dendrogenesis, and in young osteocytes it appears polarized towards the osteoblastic lamina.


1990 - MORPHOLOGICAL-STUDY OF INTERCELLULAR-JUNCTIONS DURING OSTEOCYTE DIFFERENTIATION [Articolo su rivista]
Palumbo, Carla; Palazzini, S; Marotti, Gastone
abstract

The study shows, by the morphological and ultrastructural viewpoints, the persistence of intercellular junctions during all the process of osteocyte differentiation.


1990 - Osteocyte Differentiation In The Tibia Of Newborn Rabbit - An Ultrastructural-Study Of The Formation Of Cytoplasmic Processes [Articolo su rivista]
Palumbo, Carla; Palazzini, Silvana; Marotti, Gastone; Zaffe, Davide
abstract

The morphological changes undergone by the osteoblast at the ultrastructural level, during its differentiation into osteocyte, were studied in the primary parallel-fibred bone of the newborn rabbit by means of incomplete three-dimensional reconstruction from partially serial-sectioned preosteocytes. The findings obtained suggest that the formation of osteocyte cytoplasmic processes is an asynchronous and asymmetrical phenomenon that seems to precede the mineralization of the organic matrix and to give rise to an asymmetrical mature osteocyte. The functions of cytoplasmic processes as regards bone formation, cell nutrition and osteoblast modulation are discussed. The mechanism by which the osteoblast 'enters' the bone matrix is hypothesized.


1990 - Structure-function relationships in the osteocyte. [Articolo su rivista]
Marotti, Gastone; Cane, V.; Palazzini, S.; Palumbo, Carla
abstract

The osteocytes might perform different functions according to their age.


1989 - Studio istochimico e ultrastrutturale della calcificazione in protesi valvolari cardiache di pericardio bovino [Articolo su rivista]
Muglia, Maria Antonietta; Zaffe, Davide; Marotti, Gastone; Gatti, Antonietta; G., Noera
abstract

É stato condotto uno studio istochimico ed ultrastrutturale su lembi valvolari cardiaci costruiti con pericardio bovino pretrattato con glutaraldeide e impiantati per 3 e 20 giorni nell'ostio della tricupside di pecora. È risultato che, già in un periodo sperimentale così breve, si attua una evidente calcificazione distrofica che inizia dalle cellule per estendersi successivamente alla sostanza fondamentale e alle fibre collagene. Il problema della fissazione, praticata prima del modellamento dei lembi valvolari protesici, viene discusso ai fini di prevenire o, quanto meno, dilazionare nel tempo la loro calcificazione.A histochemical and ultrastructural study was carried out on bioprosthetic heart valves fabricated from glutaraldehyde-treated bovine pericardium. It resulted that a periodi the mineralization first occurs in cell protoplasma and then in the ground substance and collagen fibers. The problem of fixation, made before modeling the semilunar bioprosthetic cusps, is discussed as regards the attempt to prevent or to delay their calcification.


1987 - Early stages of osteocyte differentiation: a three-dimensional ultrastructural study. [Abstract in Rivista]
Palumbo, Carla; Zaffe, Davide; Palazzini, S.; Marotti, Gastone
abstract

The osteocyte processes emrging fron the mineral-facing side are mainly involved in matrix formation and mineralization, while those of the vascular-facing side have a trophical function and probably also modulate the activity of the adjacent osteoblasts.


1987 - Indagine morfofunzionale sul processo di differenziamento dell'osteoblasta in osteocita [Articolo su rivista]
Palumbo, Carla; Zaffe, Davide; Palazzini, Silvana; Marotti, Gastone
abstract

No riassunto


1987 - Utrastruttura della placca di accrescimento fibrosa nella metafisi prossimale della tibia di coniglio [Articolo su rivista]
Marotti, Gastone; Palazzini, Silvana; Zaffe, Davide
abstract

No riassunto


1985 - A SEM study of osteocyte orientation in alternately structured osteons. [Articolo su rivista]
Marotti, Gastone; Muglia, Maria Antonietta; Zaffe, Davide
abstract

Previous morphometric analyses, carried out by means of the light microscope show the existence of a close relationship between size, shape, orientation of osteocytc lacunae and collagen texture in both woven bone and longitudinally structured secondary osteons (Marotti 1979, 1980). However these investigations, owing to the technique applied, failed to demonstrate the orientation of the triaxial osteocyte ellipsoids in lamellar bone with alternate orientation of fibers. In the present study the SEM was used to measure the sectional area and the axes of osteocyte lacunae in secondary osteons with different types of lamellation. Compact bone from tibiae of normal men of various age was etched with N/10 HCl for 90", and treated with Trypsin (80 µg/ml, pH 7.4 for 41h at 37°C) before being gold-palladium coated for the SEM analysis. The results obtained are in close agreement with those of the previous investigations as regards the orientation of osteocytes in woven bone and in longitudinally structured osteons. Tn addition they show that in lamellar osteons with alternate orientation of fibers the osteocytes are mainly located in longitudinally structured lamellae with their major axis at an angle of 26-27° with respect to the longitudinal axis of the Haversian canal.


1985 - Quantitative investigation on osteocyte canaliculi in human compact and spongy bone. [Articolo su rivista]
Marotti, Gastone; Remaggi, Francesca; Zaffe, Davide
abstract

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.


1984 - Modificazioni della struttura dell'osso osteonico nella fluorosi industriale [Changes in the structure of osteonic bone in industrial fluorosis] [Articolo su rivista]
Palazzini, Silvana; Remaggi, Francesca; Zaffe, Davide; Muglia, Maria Antonietta; Canè, Valerio; Marotti, Gastone
abstract

E stata condotta un'indagine comparativa al microscopio ottico a luce ordinaria e a luce polarizzata su sezioni centrodiafisarie di ossa metacarpali di bovini affetti da fluorosi industriale.I reperti istologici osservati concordano con quelli riportati in letteratura per quanto concerne sia la disorganizzazione del collagene sia la presenza di lacune osteocitarie anomale negli osteoni secondari. I risultati delle nostre osservazioni, in accordo con i dati morfometrici, indicano però che entrambi i tipi di lacune patologiche già descritti in letteratura, le cosiddette «mottled» ed «enlarged» lacune, sono per forma, densità e dimensioni del tutto identiche alle lacune che si trovano nell'osso a fibre intrecciate normale e che inoltre sono sempre localizzate in porzioni di osteoni secondari dove il collagene non è organizzato come di norma a lamelle ma a fibre intrecciate.Se ne deduce, contrariamente a quanto sostenuto da altri autori, che ambedue i tipi di lacune patologiche sono da considerarsi il risultato di una stessa noxa, ossia di una interferenza del fluoro sul metabolismo degli osteoblasti, con conseguente anomala deposizione di osso a fibre intrecciate negli osteoni secondari.A comparative investigation under ordinary and polarized light was carried out on metacar-pal bones from normal and fluorotic bovines. The histologic findings agree with those reported in literature as regards the disorganisation of collagen and the presence of abnormal osteocyte lacunae in the secondary osteons (Fig 1). Three types of pathologic haversian systems were observed: osteons with large lacunae near the cement line, osteons with «mottled lacunae», and osteons with lacunae showing an intermediate aspect (Fig. 2). Microradiographic analysis showed patches of lower degree of radiopacity in «mottled» areas, but the former appears of lower extension than the latter (Fig. 2b). The results of our observations, in agreement with the morphometric data (Fig 6), show that both types of pathologic lacunae described in literature (i.e. the so-called «mottled» and «enlarged» lacunae) are identical in shape, size and density with the lacunae found in normal woven bone (Fig 7); moreover, that these lacunae are always located in portions of secondary osteons where the collagen is not organized in lamellae, as normally, but in woven fibres (Fig 3, 4).As against what has been maintained by other authors, we conclude that both types of abnormal lacunae must considered the result of an identical pathological phenomenon: that is to say, an interference by fluoride in the metabolism of the osteoblasts, with a consequently abnormal deposit of woven bone in the secondary osteons.


1982 - Activity of osteoclasts and osteocytes in compact human bone at various ages, both with and without osteoporosis. [Articolo su rivista]
Muglia, Maria Antonietta; Volpi, Giorgia; Remaggi, Francesca; Canè, Valerio; Palazzini, Silvana; Zaffe, Davide; Marotti, Gastone
abstract

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.


1982 - Size and density of osteocyte lacunae in different regions of long bones. [Articolo su rivista]
Canè, Valerio; Marotti, Gastone; Volpi, Giorgia; Zaffe, Davide; Palazzini, Silvana; Remaggi, Francesca; Muglia, Maria Antonietta
abstract

Size and density of osteocyte lacunae were evaluated at different levels of long bones to investigate whether or not the proportion of bone tissue occupied by osteocytes changes in skeletal regions, characterized by clear-cut differences in bone turnover rates. Statistical analysis of the results shows that the mean cross-sectional area of osteocyte lacunae (C) is lowest in compact bone of diaphysis and metaphysis, highest in spongy bone of metaphysis and epiphysis. On the contrary, the mean surface of bone tissue surrounding each osteocyte (T = bidimensional osteocyte territory, indirectly calculated from the number of lacunae/mm2 of bone) is largest in compact bone of diaphysis, smallest in metaphyseal spongiosa, and shows intermediate values in the cortex of metaphysis and in epiphyseal spongiosa. The proportion of bone tissue occupied by osteocyte lacunae (% C/T) appears to follow at different levels of long bones, the same pattern recorded for the data of bone turnover rate, by the tetracycline labeling technique: it is lowest in mid-diaphyses, highest in metaphyses, and intermediate in epiphyses. On the basis of these findings, it is suggested that the action exerted by osteocytes on the surrounding calcified matrix, whatever the function of these cells, is not uniform throughout the skeleton and is to some extent correlated with the activity of the other bone cells-osteoblasts and osteoclasts.The signifìcance of some of the data reported is also discussed in relation to investigations of periosteocytic lacunar morphometry.