Journal of Anatomy最新文献

Body size has an impact on all biological functions and analyzing how body size impacts functional traits such as locomotion is critical. Body size does not only vary across species but also during ontogeny. Indeed, juvenile animals are often at a competitive disadvantage due to their smaller absolute size. Consequently, understanding size- and age-related changes in the locomotor system is critical for our understanding of adult phenotypes. Here, we address this question by exploring growth of the hind limb muscles in two species of closely related baboons that differ in their ecology, the olive baboon, Papio Anubis, the Guinea baboon, and Papio papio. To do so, we dissected 40 P. anubis and 10 P. papio and measured the mass and physiological cross-sectional area (PCSA) of the hind limb muscles. Our results showed no sexual differences in size- or age-related growth patterns, but did show differences between species. Whereas the scaling of muscle mass and PCSA was largely isometric in P. anubis, allometric scaling was more common in P. papio. Despite these differences between species, the knee extensors and external rotators at the knee scaled with positive allometry in both species highlighting their important role during adult locomotion. Although life-history data for P. papio are scarce, we suggest that differences between species may be associated with differences in adult body size and age of locomotor independence between species.

Biomechanical studies in sauropod dinosaurs are mainly focused on neck posture and feeding strategy. Few works investigate other aspects such as tail movement and function, especially in the clade Titanosauria, the most diverse within Neosauropoda. This study applied biomechanical concepts of neutral pose (cartilaginous neutral pose) and range of motion to verify the shape and direction of the caudal region of the advanced titanosaurs Adamantisaurus mezzalirai and Baurutitan britoi, in addition to comparing it with other titanosaurs (e.g., Arrudatitan maximus, Lirainosaurus astibiae, and Trigonosaurus pricei). As a result, the tails analyzed have a sigmoidal-convex shape, probably close to the ground (but not touching it). The sigmoidal-convex shape could increase the moment arm for the M. caudofemoralis longus, making it possible to use the tail as a fifth stabilizing member. This work expands our knowledge about sauropod dinosaurs by exposing a diversity of shapes for the tails of titanosaur sauropods and brings new possibilities for how these dinosaurs could use their tails.

The alveolar surface of the lung is lined by an epithelium consisting of type I (AECI) and type II alveolar epithelial cells (AECII). This epithelium is covered by a liquid alveolar lining layer (ALL). Besides intra-alveolar surfactant, ALL also contains the alveolar epithelial glycocalyx on the apical side of AECI and AECII. To better understand the alveolar epithelial glycocalyx, its ultrastructural visualization by transmission electron microscopy is required. The aim of this study was to systematically re-evaluate routine cytochemical methods for visualization of the alveolar epithelial glycocalyx and specifically its glycan components. For this purpose, we used chemical fixation by vascular perfusion with aldehydes as a common routine approach in mice. After fixation, staining is needed for glycocalyx visualization. Cytochemical staining agents such as alcian blue, ruthenium red, and lanthanum nitrate were compared. In addition, SNL (Sambucus nigra lectin) and UEA1 (Ulex europaeus agglutinin I) were used for sialic acid and fucose-specific labeling. Alcian blue showed the strongest staining, with cloud-like structures, whereas ruthenium red appeared as thread-like structures. On the other hand, lanthanum nitrate did not stain the alveolar epithelial glycocalyx. For specific sialic acid and fucose labeling, both lectins presented a specific signal. In conclusion, these methods can be used routinely for assessing ultrastructural changes of the alveolar epithelial glycocalyx in experimental in vivo models under different physiological and pathological conditions. In addition, cytochemical staining by tissue massage and post-embedding lectin labeling after vascular perfusion support 3R (reduction, refinement, replacement) principles of animal welfare.

Counting growth layers in dentine and/or secondary cementum is widely used for age determination in wild mammals but the underlying seasonal changes in the structure and degree of mineralisation of dental tissue have not been well characterised. We embedded first (m1) and second (m2) mandibular permanent molar teeth from a 12-year-old female Svalbard reindeer (Rangifer tarandus platyrhynchus) in PolyMethylMethAcrylate (PMMA), prepared cut and polished surfaces coated with evaporated carbon and used 20 kV back-scattered electron imaging in a scanning electron microscope (BSE-SEM) to study aspects of dental tissue structure which depend on the degree of mineralisation at the micron and sub-micron scale. BSE-SEM revealed differences between the mineral content of growth layers (annulations) in the secondary cementum and the primary and secondary dentine, the latter, incidentally, still forming at death in m1. Wide bands of less well mineralised tissue formed in the cementum during active appositional phases. Thin, denser bands formed by maturation-mineralisation of existing tissue when growth slowed in winter. This maturation mimics the processes seen in lamellar bone and articular cartilage. Counter to previous suggestions, there was evidence of substantial resorption and repair of the secondary cementum and of formation of dentine throughout life. Secondary dentine is layered by mineral content like cementum. In the crown, this was mainly tubular dentine with well-marked interglobular dentine layers. In the lower pulp chamber and root, it was largely without tubules. Substantial non-mineralised spaces found at the cement-dentine junction in the root apical regions in m2 represent inclusions of the Hertwig's Epithelial Root Sheath (HERS) or the Epithelial Rests of Malassez (ERM) between the two tissues, a phenomenon which has previously only been identified in Muridae. The anatomical changes which result in the formation of the incremental lines (annulations) in dental tissues of reindeer, identified here for the first time at the micrometre level, are likely to be common across most if not all long-lived species of mammals living in seasonal environments.

The tibial tuberosity has a superficial patellar tendon-embedded portion and a deep uncalcified cartilage portion. Suppressed calcification of the tibial tuberosity leads to Osgood-Schlatter disease. The tibial tuberosity calcifies with age; load reduction degrades the cartilage matrix and promotes calcification, suggesting that reduced mechanical stimulation of the tibial tuberosity promotes calcification. However, this is yet to be clarified. Therefore, in this study, we aimed to investigate the effects of mechanical stimulation reduction on the tibial tuberosity tissue structure and calcification mechanism. Specifically, we examined the effect of load reduction on tibial tuberosity calcification in 20 male 7-week-old Wistar rats classified into two groups: hind-limb suspension (HS, n = 10) and control (CO, n = 10). We observed superficial and deep tibial tuberosities in both groups. The tibial tuberosity in the HS group had narrower areas of deep portions than did those in the CO group (p = 0.000539), and immature bone tissue and cartilage tissue were observed in the HS group. Enpp1 expression did not significantly differ between the groups (p = 0.804). In contrast, Alpl (p = 0.001) and Mmp3 (p = 0.006) expression increased whereas Timp3 expression decreased (p = 0.002) in the HS group. Thus, these results showed a maturing of bone ossification, and this gene expression trend was similar to that observed in a murine join instability model of osteoarthritis with articular cartilage calcification and ossification. The HS tibial tuberosity also showed immature bone tissue. In conclusion, reduced mechanical stimulation caused tibial tuberosity calcification and pathological changes. These findings highlight the importance of optimal exercise to avoid premature pathological structural changes in bones and joints.

Langebaanweg is a Mio-Pliocene locality located on the West Coast of South Africa. It is renowned for its rich diversity of both terrestrial and marine vertebrate fossils. Several carnivorans have been identified from this site, amongst which is the recently described jackal-like canid, Eucyon khoikhoi. One of the skeletons assigned to E. khoikhoi exhibits anatomical deformities on several bones of the skeleton. Here, we use multiple methodologies (anatomical descriptions, CT scanning and histology) to investigate the bony overgrowths or exostoses evident in the radius, and we compare these findings with those of a radius from a healthy individual of the same species from Langebaanweg. Our results show that anatomical observations are important for first level observation of the pathology, but that micro-CT scanning permits a more precise assessment of how the pathology affected the internal organization of the bone, both periosteally and endosteally. This methodology permitted us to diagnose the tumors as benign rather than cancerous. Our observations of calcified cartilage in the histological thin sections in the region of the exostosis allowed us to further diagnose the exostosis as an osteochondroma. This study has demonstrated the usefulness of applying multiple techniques to characterize and diagnose pathological bony growths in a fossil canivoran. We have also demonstrated the usefulness of histological studies in permitting a more refined diagnosis of the exostosis as an osteochondroma.

The fascial system has gained recognition for its integral role in connecting skin, superficial and deep fasciae, and underlying muscles. However, consensus on its microstructure depending on its topography remains elusive as well as its implications in clinical practices, such as reconstructive surgery and physiotherapy techniques. This study focuses on the iliotibial tract (ITT) implicated in the iliotibial band syndrome. The goal is to describe microstructural characteristics using classical 2D histology and cryogenic contrast-enhanced microcomputed tomography (cryo-CECT) such as the total thickness, number of layers, layer thickness, fibre orientation and tortuosity, according to the specific topography. The total thickness of the ITT varied across topographic regions, with the superior part being on average thicker but non-significantly different from the other regions. The inferior part showed heterogeneity, with the anterior region (AI) being the thinnest and the posterior one (PI) the thickest. The ITT exhibited 1–3 layers, with no significant differences among regions. Most commonly, it consisted of two layers, except for the antero-superior (AS) and antero-middle (AM) regions, which sometimes had only one layer. The posterior regions frequently had 2 or 3 layers, with the PI region having the highest mean (2.7 layers). The intermediate layer was the thickest one, varying from the AI region (0.368 mm ± 0.114) to the PI region (0.640 mm ± 0.305). The superficial layer showed regional variability, with the AS region being the thinnest. The deep layer appeared thinner than the superficial one. Fibre orientation analysis indicated that the intermediate layer mainly consisted of oblique longitudinal fibres, orientated downward and forward, while the superficial and deep layers had transversal or oblique transversal fibres. Cryo-CECT 3D observations confirmed these findings, revealing distinct orientations for different layers. Fibre tortuosity exhibited differences based on orientation. Transversal fibres (>65°) were significantly less tortuous than longitudinal fibres (<25°) and oblique intermediate fibres (25°–65°), aligning with 3D plot observations. This quantitative study highlights various microstructural characteristics of the ITT, offering insights into its regional variations. The analysis accuracy is increased due to the novel technology of cryo-CECT which emerges as a valuable tool for precise assessment of 3D fibre orientation and tortuosity. These findings contribute to a deeper understanding of the ITT structure, useful in clinical practices, such as reconstructive surgery and physiotherapy, and future research endeavours.

Understanding the impact that climate had in shaping cranial variation is critical for inferring the evolutionary mechanisms that played a role in human diversification. Here, we provide a comprehensive study aiming to analyze the association between climate and cranial variation of high latitude populations living in temperate to cold environments of Asia, North America, and South America. For this, we compiled a large morphometric dataset (N = 2633), which was combined with climatic and genomic data. We tested the influence of climate on the facial skeleton, nasal protrusion, and cranial vault and through multiple statistical tests at two geographical scales: intracontinental and intercontinental. We show that populations living in cold areas share a morphological pattern characterized by an increase in nasal height, facial and orbital heights and widths, a decrease in facial protrusion, and larger, longer, and lower cranial vaults. There are also distinctive features; populations from north Asia present the tallest noses, largest faces, and cranial vaults of the whole sample. Nasal breadth dimensions show small values in Asians, large values in South Americans, and non-significant changes in arctic North America. The morphological pattern in populations living at high latitude may be the result of parallel adaptation, as supported by physiological, morphometric, ecological, and genetic explanations, while the differences in magnitude and phenotypic expression could be due to the diverse population histories, severity of climate, and cultural strategies. Overall, our study shows that climate is a relevant factor shaping modern human morphology and it should be considered when studying modern human evolution and diversification.