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Hande SS, Andronowski JM, Miller EH. Microarchitecture of the penis bone (baculum) of a seal: A 3D morphometric examination using synchrotron and laboratory micro-computed tomography. Anat Rec (Hoboken) 2024; 307:2858-2874. [PMID: 38311971 DOI: 10.1002/ar.25396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/08/2024] [Accepted: 01/13/2024] [Indexed: 02/06/2024]
Abstract
We examined the ultrastructure of the mammalian os penis at the high-resolution synchrotron level. Previously, bacular microanatomy had only been investigated histologically. We studied the baculum of the harp seal (Pagophilus groenlandicus), in which the baculum varies more in size and shape than does a mechanically constrained bone (humerus). We (1) investigated the microarchitecture of bacula and humeri from the same seal specimens, and (2) described changes in bone micro- and macro-morphology associated with age (n = 15, age range = 1-35 years) and bone type. We analyzed cross-sectional geometry non-destructively through laboratory micro-computed tomography. We suggest that the midshaft may resist axial compression while the proximal region may resist torsion, based on measurements of cross-sectional and cortical areas, perimeter, ratio of maximum and minimum moments of inertia, and polar moment of inertia. In addition, midshaft bacula may be less mechanosensitive than humeri, based on microstructural variables (e.g., volume, surface area, diameter associated with lacunae and cortical porosity) analyzed across age groupings. Our findings related to the microarchitecture of the pinniped baculum provide a basis for further studies on development, mechanical properties, functions, and adaptations in this and other pinniped species. Our use of a multi-modal imaging approach was minimally destructive for reproducible and accurate comparison of three-dimensional bone ultrastructure. Such methods, coupled with multidisciplinary analyses, enable diverse studies of bone biology, life history, and evolution using museum collections.
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Affiliation(s)
- Shreya S Hande
- Department of Biology, Memorial University of Newfoundland, Canada
| | - Janna M Andronowski
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Canada
| | - Edward H Miller
- Department of Biology, Memorial University of Newfoundland, Canada
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2
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Jadwiszczak P, Krüger A, Mörs T. Fossil and modern penguin tarsometatarsi: cavities, vascularity, and resilience. Integr Zool 2024. [PMID: 38858828 DOI: 10.1111/1749-4877.12852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Penguin tarsometatarsi are shortened and flattened, and studies devoted to the internal characteristics of these composite bones are very limited. Therefore, we present here a comprehensive, x-ray-microscopy-based analysis based on tarsometatarsi of Eocene stem Sphenisciformes from Seymour Island (Antarctic Peninsula) as well as recent Aptenodytes forsteri, A. patagonicus, and Pygoscelis adeliae penguins. Our study focuses on four aspects: size variability of the medullary cavities, vascularization patterns with emphasis on diaphyseal vessels, cross-sectional anisotropy, and diaphyseal resistance to bending forces. Small-sized Eocene penguins (Delphinornis and Marambiornopsis) show well-developed tarsometatarsal medullary cavities, whereas the cavities of "giant" early Sphenisciformes are either smaller (Palaeeudyptes) or show a conspicuous intermetatarsal size gradient (Anthropornis). Extant penguins exhibit a decrease in cavity dimensions as their body size increases. Distributional tendencies of primary diaphyseal nutrient foramina are quite similar in the smaller Delphinornis, Marambiornopsis, and extant Pygoscelis on one side and in Palaeeudyptes and extant Aptenodytes on the other. Anthropornis shows a unique, plesiomorphic pattern with a prevalence of plantar blood supply to the metatarsals. The diaphyseal nutrient canals diverge in orientation, some obliquely away from the proximal part, others with disparate trajectories. Cross-sectional anisotropy along the tarsometatarsal shaft generally appears to be rather low. Clustering of coherency curves along certain tarsometatarsal segments may reflect a selection process that exerts a significant influence within biomechanically crucial sections. Diaphyseal resistance to mediolateral bending forces is explicitly more efficient in extant penguins than in Eocene Sphenisciformes. This can be interpreted as an adaptation to the waddling gait of extant penguins.
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Affiliation(s)
| | - Ashley Krüger
- Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
| | - Thomas Mörs
- Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
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3
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Frongia GN, Naitana S, Farina V, Gadau SD, Stefano MD, Muzzeddu M, Leoni G, Zedda M. Correlation between wing bone microstructure and different flight styles: The case of the griffon vulture (gyps fulvus) and greater flamingo (phoenicopterus roseus). J Anat 2021; 239:59-69. [PMID: 33650143 PMCID: PMC8197951 DOI: 10.1111/joa.13411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 02/02/2021] [Accepted: 02/02/2021] [Indexed: 12/30/2022] Open
Abstract
Flying is the main means of locomotion for most avian species, and it requires a series of adaptations of the skeleton and of feather distribution on the wing. Flight type is directly associated with the mechanical constraints during flight, which condition both the morphology and microscopic structure of the bones. Three primary flight styles are adopted by avian species: flapping, gliding, and soaring, with different loads among the main wing bones. The purpose of this study was to evaluate the cross-sectional microstructure of the most important skeletal wing bones, humerus, radius, ulna, and carpometacarpus, in griffon vultures (Gyps fulvus) and greater flamingos (Phoenicopterus roseus). These two species show a flapping and soaring flight style, respectively. Densitometry, morphology, and laminarity index were assessed from the main bones of the wing of 10 griffon vultures and 10 flamingos. Regarding bone mineral content, griffon vultures generally displayed a higher mineral density than flamingos. Regarding the morphology of the crucial wing bones involved in flight, while a very slightly longer humerus was observed in the radius and ulna of flamingos, the ulna in griffons was clearly longer than other bones. The laminarity index was significantly higher in griffons. The results of the present study highlight how the mechanics of different types of flight may affect the biomechanical properties of the wing bones most engaged during flight.
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Affiliation(s)
| | | | | | | | - Marco D. Stefano
- Departments of Internal Medicine, Gerontology and Bone Metabolic Disease SectionMolinette HospitalUniversity of TurinItaly
| | - Marco Muzzeddu
- Bonassai Breeding and Wildlife Recovery CenterRegional Forest Agency FoReSTASCagliariItaly
| | - Giovanni Leoni
- Department of Veterinary MedicineUniversity of SassariItaly
| | - Marco Zedda
- Department of Veterinary MedicineUniversity of SassariItaly
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4
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Williams KA, Gostling NJ, Steer JW, Oreffo ROC, Schneider P. Quantifying intracortical bone microstructure: A critical appraisal of 2D and 3D approaches for assessing vascular canals and osteocyte lacunae. J Anat 2020; 238:653-668. [PMID: 33090473 PMCID: PMC7855084 DOI: 10.1111/joa.13325] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 09/04/2020] [Accepted: 09/10/2020] [Indexed: 02/04/2023] Open
Abstract
Describing and quantifying vascular canal orientation and volume of osteocyte lacunae in bone is important in studies of bone growth, mechanics, health and disease. It is also an important element in analysing fossil bone in palaeohistology, key to understanding the growth, life and death of extinct animals. Often, bone microstructure is studied using two-dimensional (2D) sections, and three-dimensional (3D) shape and orientation of structures are estimated by modelling the structures using idealised geometries based on information from their cross sections. However, these methods rely on structures meeting strict geometric assumptions. Recently, 3D methods have been proposed which could provide a more accurate and robust approach to bone histology, but these have not been tested in direct comparison with their 2D counterparts in terms of accuracy and sensitivity to deviations from model assumptions. We compared 2D and 3D methodologies for estimating key microstructural traits using a combination of experimental and idealised test data sets. We generated populations of cylinders (canals) and ellipsoids (osteocyte lacunae), varying the cross-sectional aspect ratios of cylinders and orientation of ellipsoids to test sensitivity to deviations from cylindricality and longitudinal orientation, respectively. Using published methods, based on 2D sections and 3D data sets, we estimated cylinder orientation and ellipsoid volume. We applied the same methods to six CT data sets of duck cortical bone, using the full volumes for 3D measurements and single CT slices to represent 2D sections. Using in silico test data sets that did deviate from ideal cylinders and ellipsoids resulted in inaccurate estimates of cylinder or canal orientation, and reduced accuracy in estimates of ellipsoid and lacunar volume. These results highlight the importance of using appropriate 3D imaging and quantitative methods for quantifying volume and orientation of 3D structures and offer approaches to significantly enhance our understanding of bone physiology based on accurate measures for bone microstructures.
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Affiliation(s)
- Katherine A. Williams
- Bioengineering Science Research GroupFaculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonUnited Kingdom
| | - Neil J. Gostling
- School of Biological SciencesFaculty of Environmental and Biological SciencesUniversity of SouthamptonSouthamptonUnited Kingdom
| | - Joshua W. Steer
- Bioengineering Science Research GroupFaculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonUnited Kingdom
| | - Richard O. C. Oreffo
- Bone and Joint Research GroupCentre for Human DevelopmentStem Cells and RegenerationInstitute of Developmental SciencesFaculty of MedicineUniversity of SouthamptonSouthamptonUnited Kingdom
| | - Philipp Schneider
- Bioengineering Science Research GroupFaculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonUnited Kingdom
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5
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Yan J, Zhang Z. Post-hatching growth of the limbs in an altricial bird species. Vet Med Sci 2020; 7:210-218. [PMID: 32937037 PMCID: PMC7840189 DOI: 10.1002/vms3.357] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 07/23/2020] [Accepted: 08/29/2020] [Indexed: 11/28/2022] Open
Abstract
The fore‐ and hindlimbs of birds are specialized to perform different functions. The growth patterns of limb bones and their relationship with the ontogeny of locomotion are critical to our understanding of variation in morphological, physiological and life‐history traits within and among species. Unfortunately, the ontogenetic development of limb bones has not been well explored, especially in altricial birds. In this study, we sampled the entire measurements of the pigeon (Columba livia) of individual skeletons, to investigate the ontogenetic allometry of limb bones by reduced major axis regression. The ulna and humerus were found to be positively allometric in relation to body mass, with the ulna growing more rapidly than the humerus. Together with previous data, this suggests that strong positive allometric growth in forelimb bones could be a common trend among diverse Carinatae groups. Hindlimb was dominated by positive allometry, but was variable in the growth of the tarsometatarsus which included three allometric patterns. A greater dorsoventral diameter in the midsection of the humerus and ulna confers superior bending resistance and is ideal for flapping/gliding flight. Shape variation in the midsection of different hindlimb components reflects different mechanical loading, and the markedly inverse trend between the tibiotarsus and tarsometatarsus before 28 days of age also suggests loading change before fledging. Before fledging, the growth of the leg bones was prior to that of the wing bones. This kind of asynchronous development of the fore‐ and hindlimbs was associated with the establishment and improvement of different functions, and with shifts in the importance of different functions over time.
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Affiliation(s)
- Jianjian Yan
- College of Life Sciences, Capital Normal University, Beijing, China
| | - Zihui Zhang
- College of Life Sciences, Capital Normal University, Beijing, China
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6
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Prondvai E, Witten PE, Abourachid A, Huysseune A, Adriaens D. Extensive chondroid bone in juvenile duck limbs hints at accelerated growth mechanism in avian skeletogenesis. J Anat 2019; 236:463-473. [PMID: 31670843 PMCID: PMC7018642 DOI: 10.1111/joa.13109] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2019] [Indexed: 12/03/2022] Open
Abstract
Modern altricial birds are the fastest growing vertebrates, whereas various degrees of precocity (functional maturity) result in slower growth. Diaphyseal osteohistology, the best proxy for inferring relative growth rates in fossils, suggests that in the earliest birds, posthatching growth rates were more variable than in modern representatives, with some showing considerably slow growth that was attributed to their assumed precocial flight abilities. For finding clues how precocial or altricial skeletogenesis and related growth acceleration could be traced in avian evolution, as a case study we investigated the growing limb diaphyseal histology in an ontogenetic series of ducks which, among several other avian taxa, show a combination of altricial wing and precocial leg development. Here we report the unexpected discovery that chondroid bone, a skeletal tissue family intermediate between cartilage and bone, extensively contributes to the development of limb bone shaft in ducks up to at least 30 days posthatching age. To our knowledge, chondroid bone has never been reported in such quantities and with an ontogenetically extended deposition period in post‐embryonic, non‐pathological periosteal bone formation of any tetrapod limb. It shows transitional cellular/lacunar morphologies and matrix staining properties between cartilage and woven bone and takes a significant part in the diametric growth of the limb bone shaft. Its amount and distribution through duckling ontogeny seems to be associated with the disparate functional and growth trajectories of the altricial wings vs. precocial legs characteristic of duck limb development. The presence of isogenous cell groups in the periosteal chondroid bone implies that cartilage‐like interstitial growth took place before matrix mineralization complementing appositional bone growth. Based on these characteristics and on its fast formation rate in all previously reported normal as well as pathological cases, we suggest that chondroid bone in ducks significantly accelerates diametric limb bone growth. Related to this growth acceleration, we hypothesize that chondroid bone may be generally present in the growing limb bones of modern birds and hence may have key skeletogenic importance in achieving extreme avian growth rates and placing birds among the fastest growing vertebrates. Thus, we encourage future studies to test this hypothesis by investigating the occurrence of chondroid bone in a variety of precocial and altricial bird species, and to explore the presence of similar tissues in the growing limbs of other extant and extinct tetrapods in order to understand the evolutionary significance of chondroid bone in accelerated appendicular skeletogenesis.
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Affiliation(s)
- Edina Prondvai
- Department of Biology, Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium.,MTA-MTM-ELTE Research Group for Paleontology, Budapest, Hungary
| | - P Eckhard Witten
- Department of Biology, Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
| | - Anick Abourachid
- Département Adaptations du Vivant, UMR 7179 Muséum National d'Histoire Naturelle - CNRS, Paris, France
| | - Ann Huysseune
- Department of Biology, Evolutionary Developmental Biology, Ghent University, Ghent, Belgium
| | - Dominique Adriaens
- Department of Biology, Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium
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7
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Kuehn AL, Lee AH, Main RP, Simons ELR. The effects of growth rate and biomechanical loading on bone laminarity within the emu skeleton. PeerJ 2019; 7:e7616. [PMID: 31579580 PMCID: PMC6765378 DOI: 10.7717/peerj.7616] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 08/05/2019] [Indexed: 12/27/2022] Open
Abstract
The orientation of vascular canals in primary bone may reflect differences in growth rate and/or adaptation to biomechanical loads. Previous studies link specific canal orientations to bone growth rates, but results between different taxa are contradictory. Circumferential vascular canals (forming laminar bone) have been hypothesized to reflect either (or both) rapid growth rate or locomotion-induced torsional loading. Previous work on the hindlimb biomechanics in the emu shows that the femur and tibiotarsus experience large shear strains, likely resulting from torsional loads that increase through ontogeny. Here, we test how growth rate and biomechanical loading affect bone laminarity in wing and hindlimb elements from growing emu (2–60 wks). If laminar bone is an adaptation to torsion-induced shear strains, it should increase from juveniles to adults. Alternatively, if bone laminarity reflects rapid growth, as has been shown previously in emu, it should be abundant in fast-growing juveniles and decrease with age. Transverse mid-shaft histological sections from the limb bones (femur, tibiotarsus, humerus, ulna, and radius) were prepared and imaged. Growth rates were measured using fluorescent bone labels. Vascular canal orientation was quantified using laminarity index (proportion of circumferential canals). Principal components analysis was performed to convert highly correlated variables (i.e., mass, age, growth rate, and shear strain) into principal components. Random-intercept beta regression modeling determined which principal components best explained laminarity. The fastest growth rates were found in young individuals for all five skeletal elements. Maximum growth rate did not coincide with peak laminarity. Instead, in the femur and tibiotarsus, elevated laminarity is strongly correlated with adult features such as large size, old age, and modest growth rate. This result is contrary to predictions made based on a previous study of emu but is consistent with results observed in some other avian species (penguin, chicken). Shear strain in the caudal octant of the femur and tibiotarsus is positively correlated with laminarity but has a weaker effect on laminarity relative to mass, age, and growth rate. Laminarity in the wing elements is variable and does not correlate with ontogenetic factors (including mass, age, and growth rate). Its presence may relate to relaxed developmental canalization or a retained ancestral feature. In conclusion, ontogeny (including growth rate) is the dominant influence on vascular canal orientation at least in the hindlimb of the emu.
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Affiliation(s)
- Amanda L Kuehn
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, United States of America
| | - Andrew H Lee
- Department of Anatomy, College of Graduate Studies, Arizona College of Osteopathic Medicine, College of Veterinary Medicine, Midwestern University, Glendale, AZ, United States of America
| | - Russell P Main
- College of Veterinary Medicine, Purdue University, West Lafayette, IN, United States of America
| | - Erin L R Simons
- Department of Anatomy, College of Graduate Studies, Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ, United States of America
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Skedros JG, Doutré MS. Collagen fiber orientation pattern, osteon morphology and distribution, and presence of laminar histology do not distinguish torsion from bending in bat and pigeon wing bones. J Anat 2019; 234:748-763. [PMID: 30924933 DOI: 10.1111/joa.12981] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2019] [Indexed: 12/17/2022] Open
Abstract
Bone can adapt to its habitual load history at various levels of its hierarchical structural and material organization. However, it is unclear how strongly a bone's structural characteristics (e.g. cross-sectional shape) are linked to microstructural characteristics (e.g. distributions of osteons and their vascular canals) or ultrastructural characteristics [e.g. patterns of predominant collagen fiber orientation (CFO)]. We compared the cross-sectional geometry, microstructure and ultrastructure of pigeon (Columba livia domestica) humeri, and third metacarpals (B3M) and humeri of a large bat (Pteropus poliocephalus). The pigeon humerus is habitually torsionally loaded, and has unremodeled ('primary') bone with vessels (secondary osteons are absent) and high 'laminarity' because a large majority of these vessels course circularly with respect to the bone's external surface. In vivo data show that the bat humerus is also habitually torsionally loaded; this contrasts with habitual single-plane bending of the B3M, where in vivo data show that it oscillates back and forth in the same direction. In contrast to pigeon humeri where laminar bone is present, the primary tissue of these bat bones is largely avascular, but secondary osteons are present and are usually in the deeper cortex. Nevertheless, the load history of humeri of both species is prevalent/predominant torsion, producing diffusely distributed shear stresses throughout the cross-section. We tested the hypothesis that despite microstructural/osteonal differences in these pigeon and bat bones, they will have similar characteristics at the ultrastructural level that adapt each bone for its load history. We postulate that predominant CFO is this characteristic. However, even though data reported in prior studies of bones of non-flying mammals suggest that CFO would show regional variations in accordance with the habitual 'tension regions' and 'compression regions' in the direction of unidirectional habitual bending, we hypothesized that alternating directions of bending within the same plane would obviate these regional/site-specific adaptations in the B3M. Similarly, but for other reasons, we did not expect regional variations in CFO in the habitually torsionally loaded bat and pigeon humeri because uniformly oblique-to-transverse CFO is the adaptation expected for the diffusely distributed shear stresses produced by torsion/multidirectional loads. We analyzed transverse sections from mid-diaphyses of adult bones for CFO, secondary osteon characteristics (size, shape and population density), cortical thickness in quadrants of the cortex, and additional measures of cross-sectional geometry, including the degree of circular shape that can help distinguish habitual torsion from bending. Results showed the expected lack of regional CFO differences in quasi-circular shaped, and torsionally loaded, pigeon and bat humeri. As expected, the B3M also lacked CFO variations between the opposing cortices along the plane of bending, and the quasi-elliptical cross-sectional shape and regional microstructural/osteonal variations expected for bending were not found. These findings in the B3M show that uniformity in CFO does not always reflect habitual torsional loads. Osteon morphology and distribution, and presence of laminar histology also do not distinguish torsion from bending in these bat and pigeon wing bones.
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Affiliation(s)
- John G Skedros
- Bone and Joint Research Laboratory, George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Department of Orthopaedic Surgery, The University of Utah, Salt Lake City, UT, USA
| | - Madison S Doutré
- Bone and Joint Research Laboratory, George E. Whalen Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
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9
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Frongia GN, Muzzeddu M, Mereu P, Leoni G, Berlinguer F, Zedda M, Farina V, Satta V, Di Stefano M, Naitana S. Structural features of cross-sectional wing bones in the griffon vulture (Gyps fulvus)as a prediction of flight style. J Morphol 2018; 279:1753-1763. [DOI: 10.1002/jmor.20893] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 07/18/2018] [Accepted: 08/05/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Gian N. Frongia
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
| | - Marco Muzzeddu
- Bonassai Breeding and Wildlife Recovery Center; Regional Forest Agency FoReSTAS, Viale Merello; Cagliari Italy
| | - Paolo Mereu
- Department of Biomedical Sciences; University of Sassari, Via Muroni; Sassari Italy
| | - Giovanni Leoni
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
| | - Fiammetta Berlinguer
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
| | - Marco Zedda
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
| | - Vittorio Farina
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
| | - Valentina Satta
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
| | - Marco Di Stefano
- Departments of Internal Medicine, Gerontology and Bone Metabolic Disease Section; Molinette Hospital, University of Turin, Corso Bramante; Turin Italy
| | - Salvatore Naitana
- Department of Veterinary Medicine; University of Sassari, Via Vienna 2; Sassari Italy
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11
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Pratt IV, Johnston JD, Walker E, Cooper DML. Interpreting the three-dimensional orientation of vascular canals and cross-sectional geometry of cortical bone in birds and bats. J Anat 2018; 232:931-942. [PMID: 29520776 PMCID: PMC5979616 DOI: 10.1111/joa.12803] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2018] [Indexed: 01/01/2023] Open
Abstract
Cortical bone porosity and specifically the orientation of vascular canals is an area of growing interest in biomedical research and comparative/paleontological anatomy. The potential to explain microstructural adaptation is of great interest. However, the determinants of the development of canal orientation remain unclear. Previous studies of birds have shown higher proportions of circumferential canals (called laminarity) in flight bones than in hindlimb bones, and interpreted this as a sign that circumferential canals are a feature for resistance to the torsional loading created by flight. We defined the laminarity index as the percentage of circumferential canal length out of the total canal length. In this study we examined the vascular canal network in the humerus and femur of a sample of 31 bird and 24 bat species using synchrotron micro-computed tomography (micro-CT) to look for a connection between canal orientation and functional loading. The use of micro-CT provides a full three-dimensional (3D) map of the vascular canal network and provides measurements of the 3D orientation of each canal in the whole cross-section of the bone cortex. We measured several cross-sectional geometric parameters and strength indices including principal and polar area moments of inertia, principal and polar section moduli, circularity, buckling ratio, and a weighted cortical thickness index. We found that bat cortices are relatively thicker and poorly vascularized, whereas those of birds are thinner and more highly vascularized, and that according to our cross-sectional geometric parameters, bird bones have a greater resistance to torsional stress than the bats; in particular, the humerus in birds is more adapted to resist torsional stresses than the femur. Our results show that birds have a significantly (P = 0.031) higher laminarity index than bats, with birds having a mean laminarity index of 0.183 in the humerus and 0.232 in the femur, and bats having a mean laminarity index of 0.118 in the humerus and 0.119 in the femur. Counter to our expectation, the birds had a significantly higher laminarity index in the femur than in the humerus (P = 0.035). To evaluate whether this discrepancy was a consequence of methodology we conducted a comparison between our 3D method and an analogue to two-dimensional (2D) histological measurements. This comparison revealed that 2D methods significantly underestimate (P < 0.001) the amount of longitudinal canals by an average of 20% and significantly overestimate (P < 0.001) the laminarity index by an average of 7.7%, systematically mis-estimating indices of vascular canal orientations. In comparison with our 3D results, our approximated 2D measurement had the same results for comparisons between the birds and bats but found significant differences only in the longitudinal index between the humerus and the femur for both groups. The differences between our 3D and pseudo-2D results indicate that differences between our findings and the literature may be partially based in methodology. Overall, our results do not support the hypothesis that the bones of flight are more laminar, suggesting a complex relation between functional loading and microstructural adaptation.
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Affiliation(s)
- Isaac V. Pratt
- Department of Anatomy & Cell BiologyUniversity of SaskatchewanSaskatoonSKCanada
| | - James D. Johnston
- Department of Mechanical EngineeringUniversity of SaskatchewanSaskatoonSKCanada
| | - Ernie Walker
- Department of Archaeology & AnthropologyUniversity of SaskatchewanSaskatoonSKCanada
| | - David M. L. Cooper
- Department of Anatomy & Cell BiologyUniversity of SaskatchewanSaskatoonSKCanada
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12
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Pratt IV, Cooper DML. A method for measuring the three-dimensional orientation of cortical canals with implications for comparative analysis of bone microstructure in vertebrates. Micron 2017; 92:32-38. [DOI: 10.1016/j.micron.2016.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/31/2016] [Accepted: 10/31/2016] [Indexed: 01/02/2023]
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13
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Stewart MC, Goliath JR, Stout SD, Hubbe M. Intraskeletal Variability of Relative Cortical Area in Humans. Anat Rec (Hoboken) 2015; 298:1635-43. [PMID: 26058578 DOI: 10.1002/ar.23181] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 03/26/2015] [Accepted: 04/20/2015] [Indexed: 11/11/2022]
Abstract
Histomorphometric and cross-sectional geometric studies of bone have provided valuable information about age at death, behavioral and activity patterns, and pathological conditions for past and present human populations. While a considerable amount of exploratory and applied research has been completed using histomorphometric and cross-sectional geometric properties, the effects of intraskeletal variability on interpreting observed histomorphometric data have not been fully explored. The purpose of this study is to quantify intraskeletal variability in the relative cortical area of long bones and ribs from modern humans. To examine intraskeletal variability, cross-sections of the femur, tibia, fibula, humerus, radius, ulna, and rib when present, were examined within individuals from a cadaveric collection (N = 34). Relative cortical area was compared within individuals using a repeated measurements General Linear Model, which shows significant differences between bones, particularly between the rib and the remaining long bones. Complementarily, correlations between bones' relative cortical area values suggest an important allometric component affecting this aspect of long bones, but not of the rib. This study highlights the magnitude of intraskeletal variability in relative cortical area in the human skeleton, and because the relative cortical area of any particular bone is affected by a series of confounding factors, extrapolation of relative cortical area values to infer load history for other skeletal elements can be misleading.
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Affiliation(s)
- Marissa C Stewart
- Department of Anthropology, The Ohio State University, Columbus, Ohio
| | - Jesse R Goliath
- Department of Anthropology, The Ohio State University, Columbus, Ohio
| | - Sam D Stout
- Department of Anthropology, The Ohio State University, Columbus, Ohio
| | - Mark Hubbe
- Department of Anthropology, The Ohio State University, Columbus, Ohio.,Instituto de Investigaciones Arqueológicas y Museo, Universidad Católica del Norte, San Pedro de Atacama, Chile
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Lee AH, Simons ELR. Wing bone laminarity is not an adaptation for torsional resistance in bats. PeerJ 2015; 3:e823. [PMID: 25780775 PMCID: PMC4359045 DOI: 10.7717/peerj.823] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 02/16/2015] [Indexed: 12/16/2022] Open
Abstract
Torsional loading is a common feature of skeletal biomechanics during vertebrate flight. The importance of resisting torsional loads is best illustrated by the convergence of wing bone structure (e.g., long with thin walls) across extant bats and birds. Whether or not such a convergence occurs at the microstructural level is less clear. In volant birds, the humeri and ulnae often contain abundant laminar bony tissue in which primary circumferential vascular canals course concentrically about the long axis of the bone. These circumferential canals and the matrix surrounding them presumably function to resist the tissue-level shear stress caused by flight-induced torsion. Here, we assess whether or not laminar bone is a general adaptive feature in extant flying vertebrates using a histological analysis of bat bones. We sampled the humeri from six adult taxa representing a broad phylogenetic and body size range (6–1,000 g). Transverse thick sections were prepared from the midshaft of each humerus. Bone tissue was classified based on the predominant orientation of primary vascular canals. Our results show that humeri from bats across a wide phylogenetic and body size range do not contain any laminar bone. Instead, humeri are essentially avascular in bats below about 100 g and are poorly vascularized with occasional longitudinal to slightly radial canals in large bats. In contrast, humeri from birds across a comparable size range (40–1,000 g) are highly vascularized with a wide range in bone laminarity. Phylogenetically-informed scaling analyses reveal that the difference in vascularity between birds and bats is best explained by higher somatic relative growth rates in birds. The presence of wing bone laminarity in birds and its absence in bats suggests that laminar bone is not a necessary biomechanical feature in flying vertebrates and may be apomorphic to birds.
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Affiliation(s)
- Andrew H Lee
- Department of Anatomy, Midwestern University , Glendale, AZ , USA
| | - Erin L R Simons
- Department of Anatomy, Midwestern University , Glendale, AZ , USA
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