Gian Luigi Panattoni

Densitometric study of developing femur.

Abstract. The purpose of this work was to extend to long bones the study on the ossification of human fetal skeleton in relation to conceptual age by a quantitative methodological approach. Postero-anterior scans were performed on 29 dried fetal femora (from 11.5 weeks of conceptual age to term) by a Hologic QDR 1000 X-ray densitometer with Ultra-Hi-Resolution software. The results were expressed as bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2). BMD was calculated on a rectangular area corresponding to the total length and minimum width of the shaft. This area was divided into five equal sections along its longitudinal axis in order to estimate the rate of ossification from a spatio-temporal point of view. Our data show that BMC has a high correlation with conceptual age during the whole prenatal life, increasing in the third trimester (r ≥ 0.96). During development, BMD is progressively less correlated with conceptual age (r = 0.95 in the first half of development, r = 0.68 in the second half), particularly according to a bidirectional gradient from the middle to the proximal and distal ends of the shaft. Our findings confirm the data obtained in our previous studies on the ossification of fetal human spines, and suggest an individual variability in bone density at term of development and particularly at the level of spongiosa, viz. in the areas mostly involved in architectural changes during the morphogenesis of the long bones.

Densitometric Study of Dry Human Mandible

The purpose of this study was to evaluate the variability of bone density among three zones of adult human dry mandible and its relationship to age, gender, and dental status. Thirty-one dried mandibles (16 female ranging between 23 and 82 yr and 15 male ranging between 34 and 85 yr; 6 samples completely edentulous and 6 edentulous only in the molar-premolar zone) were analyzed by a Hologic QDR 1000 X-ray densitometer according to three zones: the ramus, the molar-premolar zone, and the incisor-canine zone. We found a significant inverse correlation between bone density of the ramus and age (r = 0.41, p = 0.02). The bone density of the incisor-canine zone was higher than the density of the other zones; males had a higher bone density than females in all zones analyzed. Our data suggest that mandibular bone density is influenced by age and gender in different ways according to the specific mandibular portion considered, whereas the dental status does not seem to influence mandibular bone density.

Ossification Centers of Human Femur

Abstract. The purpose of the present work was to investigate the appearance of ossification centers in human femur by Dual-energy X-ray Absorptiometry (DXA), comparing densitometric data with morphogenetic events. Postero-anterior scans were performed on 31 dried femora (from 11.5 weeks of conceptual age to 1 year of postnatal life) by a Hologic QDR 1000 X-ray densitometer with Ultra-Hi-Resolution software. The results were expressed as bone mineral content (BMC, g) and bone mineral density (BMD, g/cm2). The analyses were performed on a rectangular area corresponding to the minimum width and total length of the shaft. The rectangular area was divided into five equal sections along its longitudinal axis, and BMC was calculated on each section. To distinguish the ossification area of the lesser trochanter with respect to the area of the greater trochanter, the proximal femoral end was divided into two portions, medial and lateral, respectively; BMC and BMD were calculated on each portion. Our data show that the ossification center of the femoral shaft extends prevalently in the proximal direction. A denser area was recognizable on the densitometric images at the level of the lesser trochanter from the 19th week of prenatal life and at the level of the greater trochanter at term. During development, the trends of BMC and BMD are similar in both trochanteric areas, but these parameters are fairly constantly higher at the level of the lesser trochanter. Our findings disagree with the data of the current literature on the postnatal appearance of the trochanteric ossification centers and suggest a different biomechanical interpretation of the secondary ossification of the femur.

Ontogeny of calbindin-D28K and calretinin in developing chick kidney.

The ontogeny of two calcium-binding proteins (calbindin-D28k and calretinin) was studied by immunohistochemical techniques in developing chick kidney. This study showed the presence of calbindin on the 5th incubation day and calretinin on the 7th incubation day in mesonephric distal and connecting tubules, and in the medial wall of the Wolffian duct. At later stages, immunostaining for these two proteins, in particular for calretinin, was also demonstrated in some metanephric proximal tubules. Glomeruli and Bowmans capsules were negative both in the mesonephros and metanephros. The presence of calretinin in the developing kidney has thus been demonstrated for the first time. The early expression of calbindin and calretinin in mesonephric distal tubules suggests their role in regulating the final excretion of calcium. The different patterns of immunoreactivity of the walls of the Wolffian duct can be correlated with their different histogenetic and histological features.

Three-dimensional models of chick embryo somites obtained by mathematical methods applied to ultrastructural data

SummaryA model of a thoracolumbar somite of a chick embryo at the 53rd incubation hour was obtained by mathematical methods, after identification of somite cell types by means of electron microscopy.Each specific district occupied by the cell types was precisely determined.On the basis of these observations, the somite was three-dimensionally reconstructed and the spatial positions of the primitive myotome, dermatome, sclerotome, undifferentiated mesoderm and myocele were precisely identified.

Densitometric Study of Human Developing Dry Bones: A Review

In this article we describe the use of dual-energy X-ray absorptiometry (DXA) technique in the study of fetal and infant bone development. In particular, we review the results of densitometric studies on human developing dry bones such as spine, femur, and mandible; these data are compared with the results obtained with other methods used in the past. In particular DXA technique applied in dry is able to detect the first appearances of the ossification centers; show individual variability of bone mineral density yet during the prenatal life; and determine the correlation between bone mineral density and the variation of mechanical loading.

SOMITIC TOPOGRAPHY, SCLEROTOMAL DIFFERENTIATION AND VERTEBRAL DEVELOPMENT IN THE EARLY CHICK EMBRYO

SUMMARY Following previous work on the three-dimensional morphology of the somites and developing spinal ganglia, sclerotomal differentiation and the first phase of vertebral development were studied by typing the somitic cellular territories using L.M. and T.E.M. for the analysis of 30 chick embryos (from the 51st hour to the 5th day of incubation). Two distinct territories were identified in the ventro-medial portion of the somite: the undifferentiated somitic mesoderm, loose, with polymorphous cells, located in the cranial half of the somite; the sclerotome, dense, with smaller and ovoidal cells, located in the caudal half of the somite and with a trend to extend in a ventro-medial and caudal direction. Moreover, it was possible to reconstruct the mechanism of the formation of the vertebral body, after the fusion, around the notochord, of homologous sclerotomes, situated from the beginning of their differentiation at a more caudal level with respect to the myotomes and spinal nerves. Rejecting the theo...

Preliminary result on trabecular bone score (TBS) in lumbar vertebrae with experimentally altered microarchitecture

The aim of this preliminary research is to investigate the reliability of a new qualitative parameter, called Trabecular Bone Score (TBS), recently proposed for evaluating the microarchitectural arrangement of cancellous bone in scans carried out by dual energy X-ray absorptiometry (DXA). Vertebral bodies of 15 fresh samples of lumbar spines of adult pig were analysed either in basal conditions and with altered microarchitecture of the cancellous bone obtained by progressive drilling. The examined bony areas do not show changes in bone mineral density (BMD), whereas TBS values decrease with the increasing alteration of the vertebral microtrabecular structure. Our preliminary data seem to confirm the reliability of TBS as a qualitative parameter useful for evaluating the microarchitectural strength in bony areas quantitatively analysed by DXA.

Three-dimensional models of chick embryo somites obtained by mathematical methods applied to ultrastructural data : Part II. Lumbo-caudal and caudal somites

SummaryUsing the same methods as for the reconstruction of the thoracolumbar somite (Part I) the three-dimensional models of the lumbo-caudal and caudal somites of chick embryo (53 h of incubation) were obtained.The variations in volume, morphology, spatial position of the whole somites and of their components were studied and the development of the paraxial mesodermal structures is discussed.