Calibration of life history traits with epiphyseal closure, dental eruption and bone histology in captive and wild red deer.

The study of skeletochronology and bone tissue as a record of information on ontogenetic stages and events is widely used for improving the knowledge about life histories (LHs) of extinct and extant vertebrates. Compared with dinosaurs and extant reptiles, mammalian bone histology has received little attention. Here, we calibrate for the first time bone and dental age with histological bone characteristics and LH stages in ontogenetic series of red deer. We rely on known LHs of different aged individuals of captive Cervus elaphus hippelaphus from Austria to correlate epiphyseal closure, dental eruption pattern, bone growth marks and bone tissue patterns in femora and tibiae, and of wild Cervus elaphus hispanicus from Spain. Our data show that females (of both subspecies) attain skeletal maturity earlier than males. At this moment, epiphyseal closure (in femora and tibiae) and dental eruption are complete and long bones start to deposit an external fundamental system. The results also show that the attainment of reproductive maturity in red deer occurs slightly before skeletal maturity.

Epiphyseal fusion in Pan troglodytes relative to dental age.

Previous studies on different aspects of chimpanzee growth and development have documented dental eruption and development, long bone and somatic growth, and to a lesser extent, skeletal fusion. Such data are useful in comparative and evolutionary studies of growth and some aspects of life history evolution in apes and early hominids. However, few studies have integrated dental development and other aspects of skeletal development, and none of these have been able to incorporate a large study sample. This study documents dental mineralization and skeletal epiphyseal fusion in a mixed-sex sample of 155 Pan troglodytes skeletons, and aims to: a) document the pattern of dental and skeletal developmental in chimpanzees; b) compare male and female developmental patterns in chimpanzees; and c) compare these chimpanzee developmental patterns to general patterns of dental and skeletal development in published human studies. The analysis of both dental and skeletal development in this sample demonstrates clearly that dental development is complete before the fusion of the many skeletal epiphyses, in contrast to the pattern observed in humans. Age estimates for individuals were calculated using previously published regression equations for dental development and used to estimate fusion ages. These appear to be accurate in that our estimates are similar to published ranges. These data improve our understanding about chimpanzee dental and skeletal development and provide a basis for further comparison between extant apes and humans, as well as those extinct species represented by fossil partial skeletons.

Skeletal development in Pan paniscus with comparisons to Pan troglodytes.

Fusion of skeletal elements provides markers for timing of growth and is one component of a chimpanzee's physical development. Epiphyseal closure defines bone growth and signals a mature skeleton. Most of what we know about timing of development in chimpanzees derives from dental studies on Pan troglodytes. Much less is known about the sister species, Pan paniscus, with few in captivity and a wild range restricted to central Africa. Here, we report on the timing of skeletal fusion for female captive P. paniscus (n = 5) whose known ages range from 0.83 to age 11.68 years. Observations on the skeletons were made after the individuals were dissected and bones cleaned. Comparisons with 10 female captive P. troglodytes confirm a generally uniform pattern in the sequence of skeletal fusion in the two captive species. We also compared the P. paniscus to a sample of three unknown-aged female wild P. paniscus, and 10 female wild P. troglodytes of known age from the Taï National Park, Côte d'Ivoire. The sequence of teeth emergence to bone fusion is generally consistent between the two species, with slight variations in late juvenile and subadult stages. The direct-age comparisons show that skeletal growth in captive P. paniscus is accelerated compared with both captive and wild P. troglodytes populations. The skeletal data combined with dental stages have implications for estimating the life stage of immature skeletal materials of wild P. paniscus and for more broadly comparing the skeletal growth rates among captive and wild chimpanzees (Pan), Homo sapiens, and fossil hominins.

An animal model in sheep for biocompatibility testing of biomaterials in cancellous bones.

BACKGROUND: The past years have seen the development of many synthetic bone replacements. To test their biocompatibility and ability for osseointegration, osseoinduction and -conduction requires their placement within bone preferably in an animal experiment of a higher species. METHODS: A suitable experimental animal model in sheep with drill holes of 8 mm diameter and 13 mm depth within the proximal and distal humerus and femur for testing biocompatibility issues is introduced. RESULTS: This present sheep model allows the placing of up to 8 different test materials within one animal and because of the standardization of the bone defect, routine evaluation by means of histomorphometry is easily conducted. This method was used successfully in 66 White Alpine Sheep. When the drill holes were correctly placed no complications such as spontaneous fractures were encountered. CONCLUSION: This experimental animal model serves an excellent basis for testing the biocompatibility of novel biomaterials to be used as bone replacement or new bone formation enhancing materials.

Re-evaluation of the biocompatibility of bioinert ceramics in vivo.

The affinity of bone for bioinert ceramics and stainless steel was compared using calcified bone specimens. We implanted cylinders of alumina ceramics (Al2O3), zirconia ceramics (ZrO2) and SUS-316 L stainless steel into the distal femoral epiphyses of dogs and then made observations from 4 to 96 wk post-operatively. Irregularities in the histological specimens suggested the presence of artefacts due to the insertion technique. We subsequently used screws inserted into holes tapped with a tap that had a diameter identical to the screws, and observed these implants from 4 to 96 wk after insertion. There was no detectable difference in the affinity index for all three materials from 4 to 96 wk after implantation. The affinity index was calculated as the ratio of the new bone directly adjoining the implant without any intervening fibrous membrane or bone marrow to the total length of the bone-implant interface x 100%.

Effects of chitosan on rat knee cartilages.

The aim of this work is to study the effects of chitosan on rat knee cartilages. 0.2 ml of 0.1% chitosan solution pH = 6.9 were injected inside rat knees articular cavity. One, three and six weeks after injection, histological and histomorphometric studies were performed on undecalcified samples embedded in polymethylmetacrylate. Results show that after 1 and 6 weeks: (i) chitosan slows significantly (P < 0.005) the decrease in epiphyseal cartilage thicknesses and (ii) increases significantly articular cartilage chondrocyte densities (P < 0.002). However chitosan solution induces a proliferation of fibrous tissue with abundant fibroblasts, fibrocytes and monocytes inside the joint and this proliferation is still present after 6 weeks. This study suggests that chitosan could act on the growth of epiphyseal cartilage and wound healing of articular cartilage.

Assessment of dental and skeletal maturity. A new approach.

A comparison of radiographic methods of assessing skeletal and dental maturation, and an evaluation of the correlations among the various maturity indicators in the 8-12 year age range.

A longitudinal growth study: maxillary length at puberty in females.

1. A great individual variability is present in the timing of the maximum increment in ANS-PNS. 2. The maximum increment in maxillary length occurred before, as well as after, menarche, onset of epiphyseal-diaphyseal fusion, and peak of growth in height. 3. The later the maximum increment of growth occurred, the earlier menarche and onset of fusion occurred in relation to the peak. 4. The amount of growth at peak and duration of growth were not dictated by the absolute size of the maxilla at peak. 5. There was no significant difference in the amount of growth of maxillary length before or after menarche. 6. Timing of maximum increment in maxillary length was weakly correlated with onset of epiphyseal-diaphyseal fusion and menarche.

Innovative magnetic scaffolds for orthopedic tissue engineering.

The use of magnetism in tissue engineering is a very promising approach, in fact magnetic scaffolds are able not only to support tissue regeneration, but they can be activated and work like a magnet attracting functionalized magnetic nanoparticles (MNPs) injected close to the scaffold enhancing tissue regeneration. This study aimed to assess the in vivo biocompatibility and osteointegrative properties of novel magnetic scaffolds. Two hydroxyapatite/collagen (70/30 wt %) magnetic scaffolds were magnetized with two different techniques: direct nucleation of biomimetic phase and superparamagnetic nanoparticles (MNPs) on self-assembling collagen fibers (MAG-A) and scaffold impregnation in ferro-fluid solution (MAG-B). Magnetic scaffolds were implanted in rabbit distal femoral epiphysis and tibial mid-diaphysis. Histopathological screening showed no inflammatory reaction due to MNPs. Significantly higher bone healing rate (ΔBHR) results were observed in MAG-A in comparison to MAG-B. Significant differences were also found between experimental times with an increase in ΔBHR from 2 to 4 weeks for both scaffolds in trabecular bone, while only for MAG-B (23%, p < 0.05) in cortical bone. The proposed magnetic scaffolds seem to be promising for magnetic guiding in orthopedic tissue engineering applications and they will be suitable to treat also several pathologies in regenerative medicine area.

Skeletal ossification and the adolescent growth spurt.

Fourteen ossification events in the hand and wrist were studied in relation to the age of peak growth velocity in body height in fifty-two boys and thirty-six girls. The subjects were aborigines enrolled in a longitudinal growth study. Peak growth velocity and the ossification events occurred in aborigines at about the same ages as in Caucasian children. The results indicate that the ossification events can be used by the orthodontist to assess a child's growth activity. The accelerative phase of the adolescent growth spurt is accompanied by epiphyseal widths reaching diaphyseal widths in the fingers and radius and by ossification of the pisiform and hamate Stage 1. Peak growth velocity occurs at about the time of epiphyseal capping in the fingers and radius and ossification of the sesamoid and hamate Stage 2. The decelerative phase of growth is indicated by epiphyseal union in the third finger, progressively from distal to proximal phalanges, and in the radius. The value of these indicators in orthodontic practice is discussed.

[Tissue reaction after implantation of sintered porous hydroxyapatite in the distal metaphysis or epiphysis of the femur of rabbits].

The present investigator implanted sintered porous hydroxyapatite rod (phi 3 mm x 10 mm) in the distal metaphysis or epiphysis of the right femur of 40 Japanese white rabbits and studied tissue reaction around hydroxyapatite (abbreviated as HAp) with radiograms and microphotographs. As control, stainless-molybdenum alloyed (abbreviated as SMO) rod was used. In the groups with metaphyseal implantation of HAp or SMO, the distance between the center of implant and the distal femoral epiphyseal line increased during 12 weeks after operation. New bone was directly bonded to implanted material only after implantation of HAp. Ratio of length of HAp bone interface and length of HAp circumference was greater in the groups with implantation in the metaphysis 2 weeks after operation than those in the epiphysis. On the other hand, it was greater in groups with implantation in the epiphysis than those in the metaphysis 12 weeks after operation. In the groups with metaphyseal implantation of HAp, the ratio in groups 2 weeks after operation was greater than that in 12 weeks and there was a firm interrelationship between the ratio and the distance between the center of implant and the distal femoral epiphyseal line.