Journal of Anatomy最新文献

Angiogenesis in injured tendons may contribute to regeneration, but quantifying it post-injury has been mostly limited to 2D semi-quantitative histology. This study aimed to develop micro-CT as a 3D tool to quantitatively assess tendon blood vessels in an experimental animal model. Adult male Wistar rats (N = 36) had injuries induced in their Achilles tendons by needle insertion. The study included three post-injury groups: 12 hours post-injury (12H), 3 weeks post-injury (3W), and 8 weeks post-injury (8W). The uninjured left Achilles tendon served as the control for each group. Intravital cardiac perfusion with barium sulfate enhanced contrast between tendon and vasculature. Micro-CT imaging was performed on dissected tendons in proximal, middle, and distal regions to assess total volume, object count, and structural thickness from 3D reconstructions. Control tendons showed region-specific and age-related vascular changes, with a significant portion of blood supply originating from the muscle-tendon junction. Injury-induced vascular changes were detected by 3D micro-CT analysis. The 12H, 3W, and 8W groups exhibited increased total volume, structural thickness, and object volume in all tendon regions compared to controls (p < 0.05). Structure separation was also higher in the middle and distal regions of these groups (p < 0.05). Micro-CT combined with intravital contrast perfusion allows for 3D quantification of Achilles tendon angiogenesis, revealing a significant and sustained increase in vascularity post-injury, making it a valuable tool for studying vascularization during tendon injury and repair.

Nodal dendritic cells and CD169-positive macrophages cross-present cancer antigens earlier in the proximal nodes than in the distal nodes along the lymph flow from cancer. We examined topohistological differences between the proximal and distal nodes before the formation of metastasis. Immunohistochemical and morphometric analyses were performed to examine DC-SIGN-, CD68-, and CD169-positive cells in the subcarinal node (proximal) and paratracheal nodes (distal nodes) from 16 patients with lower-lobe lung cancer without metastasis (adenocarcinoma, 11; squamous, 5). Nodes at the same sites from 10 patients with upper-lobe cancer were used as controls. In all nodes, the medullary sinus was filled with CD68-positive and CD169-negative macrophages, most of which showed anthracosis. The proximal node carried a significantly smaller overlap between clusters of DC-SIGN-positive cells and CD169-positive cells relative to the distal node in lower-lobe cancer patients (p = 0.015). Irrespective of the cancer pathology, the tumor size was significantly correlated with the longer subcapsular clusters containing either DC-SIGN-positive cells or CD169-positive cells (p = 0.003, 0.043). A significantly small overlap between these clusters as well as the missing paracortical sinuses was evident in the negative control node outside the lymph flow (p = 0.006). Since DC-SIGN-positive cells and CD169-positive cells, especially composite cells in the overlapped cluster, are likely to be derived from monocytes, larger tumors appeared to accelerate the migration into the subcapsular sinus. In contrast to the suggested active status of the distal node, the proximal node appeared to have already been suppressed. This downregulation reached the level in the negative control node.

Unlike mammals, reptiles typically lack large muscles and ligaments that connect the zygoma to the mandible. Dinosaur craniomandibular soft tissue reconstructions, often based on the rationale of extant phylogenetic bracketing, follow this general rule. However, descending flanges from the zygomata of hadrosaurs, heterodontosaurids, and psittacosaurids have been used to argue for a masseter-like muscle in these dinosaur taxa. We examined dinosauriform skulls for osteological indicators of connective tissue entheses on the zygoma and mandible, and subsequently sectioned 10 specimens for histological evidence. Osteological indicators were found on the zygoma in most sampled dinosauriforms, which range from rugosities to large descending processes, and morphologically resemble known muscular and ligamentous entheses. Similarly, rugose features oriented towards the zygoma were found on the mandible in sampled dinosauriforms, many having previously been interpreted as entheses for the adductor mandibulae muscle group. Serial histological sectioning of ceratopsid, hadrosaurid, and tyrannosaurid jugal and surangular rugosities reveals an external cortex rich in collagen fibres, strongly resembling entheseal fibres. Jugal entheseal fibres are usually oriented ventrally towards the surangular, and in hadrosaurids and tyrannosaurids these are parallel to macroscopic striations on the surfaces of the jugal flange. Histological sections of extant chicken buccal regions show similar entheseal fibres in the attachments of the jugomandibular ligament on the jugal and of the adductor musculature on the mandible. We hypothesise a strong connective tissue structure bridging the zygoma and mandible in dinosaurs, termed the 'exoparia'. This structure's size and proximity to the craniomandibular joint would be advantageous in stabilising the mandible relative to the cranium during jaw movement, particularly in dinosaurs thought to process their masticate. A ligamentous or muscular identity for the exoparia cannot be determined with the available data, but the size and shape of the zygomatic entheses in many dinosaurs are more consistent with a muscular attachment. Possible antecedents in non-dinosauriform archosaurs and derivations in modern birds may exist, but the homology of the exoparia is currently unknown. These results highlight the complex soft tissue evolution of dinosaurs and caution against simplified phylogenetic model-based approaches to tissue reconstruction that ignore contrasting osteological signals.

Epidermal scales in sauropsids perform a wide array of biological functions, which can relate to their shape and size. Accordingly, growth-related changes in scale morphology may reflect distinct functions between juvenile and adult individuals, such as use in mating interactions. Such patterns are poorly explored in both extant reptiles and non-avian dinosaurs, limiting functional interpretations. Here, we investigate scale growth in the ornithischian ceratopsid Chasmosaurus belli and hadrosaurid Prosaurolophus maximus by comparing scale morphologies between juveniles and adults of each taxon. Scale shape is generally consistent across growth stages in both taxa, and changes in C. belli feature scale length cannot reject isometry. However, there is a greater increase in C. belli feature scale width. In practical terms, the magnitude of these size differences rejects the hypothesis that feature scale morphology played a role in mating interactions, suggesting instead that their size was largely non-adaptive. To contextualise the patterns in the sampled dinosaurs, we assessed scale growth and allometry using an ecologically diverse sample of eight extant reptile species belonging to Crocodylidae, Scincidae, Elapidae and Pythonidae. While isometry is the overall most frequent pattern of scale growth in our sample of extant reptiles, most species demonstrate positive scale allometry in at least one area of their bodies, which is likely a response to changing body proportions. Scale shapes in the studied extant species, as in both dinosaurs, are largely retained through growth. This study provides the first detailed assessment of skin growth in non-avian dinosaurs, supporting morphological stasis in the growth of most of their scales.

The fibularis longus muscle, divided into anterior and posterior neuromuscular regions, plays a significant role in eversion strength deficits in individuals with chronic ankle instability (CAI). However, it is unknown whether the muscle fiber conduction velocity (MFCV) of these neuromuscular regions is different between individuals with CAI and those without a history of ankle sprain. This study aimed to compare the MFCV of the anterior and posterior neuromuscular regions of the fibularis longus between individuals with CAI and healthy individuals. A case-control study was conducted. Thirty-five male volunteers were included in the analysis (CAI group: n = 18; No-CAI group: n = 17). High-density surface electromyography (HD-sEMG) was used to record the sEMG amplitude and to calculate the MFCV of the fibularis longus neuromuscular regions (anterior and posterior) during eversion at different contraction intensities. The findings revealed that individuals with CAI exhibited significantly lower MFCV in the posterior region at moderate (30% and 50% maximum voluntary isometric contraction [MVC]) and high (70% and 100% MVC) contraction intensities compared with healthy individuals. Within the CAI group, the posterior neuromuscular region also demonstrated a lower MFCV than the anterior neuromuscular region. These findings indicate that CAI is associated with specific regional electrophysiological changes in the fibularis longus muscle, particularly in the posterior region. Understanding these alterations can inform targeted rehabilitation strategies aimed at improving muscle function and stability in CAI patients. Future research should explore the mechanisms underlying these changes to develop more effective therapeutic interventions.

Muscle size and muscle strength gradually increase during childhood to meet the demands of a growing body. Therefore, the aim of this investigation was to establish anthropometric-related percentile curves for muscle size and strength in a cohort of typically developing (TD) children. Lower limb muscle size and strength were assessed in a large cross-sectional cohort of TD children with 3D freehand ultrasound (four muscles, n = 153 children with in total 156 measurements, male/female = 85/71, age range: 0.6-17.8 years) and fixed dynamometry (seven muscle groups, n = 153 children, male/female = 108/45, age range: 4.5-16.1 years), respectively. Generalized additive models for location, scale, and shape were used to estimate anthropometric-related, that is, body mass and height, TD percentile curves, and to convert absolute outcomes into unit-less z-scores. The results showed that both muscle size and strength, as well as their inter-subject variation, increased with increasing anthropometric values. The mean z-score of the TD children was approximately 0 ± 1 standard deviation (with the largest range from minimum to maximum of approximately -3 to 3) for all investigated muscle outcomes, confirming the fit of the percentile curves to the TD data. The use of the percentile curves was demonstrated through applications in children with cerebral palsy (CP) and Duchenne muscular dystrophy (DMD). The individual patients with CP and DMD exhibited negative z-scores, indicating muscle size and strength deficits in reference to TD peers. The established anthropometric-related percentile curves for muscle size and strength in a cohort of TD children allow for muscle outcomes to be expressed as unit-less z-scores, independent of body size, and relative to TD peers. This approach facilitates the interpretation of muscle size and strength outcomes, enabling the detection of abnormalities or deficits, monitoring of progression, and evaluation of treatment and intervention effectiveness in TD children, as well as in children with genetic, chronic neurological, or muscular disorders.

Cover image: see F. Szabó et al., ‘Chronic silencing of subsets of cortical layer 5 pyramidal neurons has a long-term influence on the laminar distribution of parvalbumin interneurons and the perineuronal nets.’ By knocking out Snap25, they abolished regulated synaptic vesicle release from different subsets of deep-layer cortical pyramidal neurons, i.e., Rbp4-Cre+ (layer 5) or Drd1a-Cre+ (layer 6b, magenta) neurons, respectively. They examined the local and global effects on the development, density, and laminar distribution of GABAergic interneurons (parvalbumin, cyan) and the perineuronal nets (detected with Vicia villosa agglutinin, yellow).

New teeth are predominantly initiated lingually or postero-lingually to the old teeth in vertebrates. Osteichthyan dentitions typically consist of linear rows of shedding teeth, but internal to the marginal jawbones osteichthyans primitively have an extra dental arcade, in which teeth are sometimes spread out into a field and not organized in rows. The tooth plates of lungfish are specialized from the jawbones of the inner dental arcade, but the teeth are arranged in radial tooth rows with new teeth added at the anterior and labial end of the rows and without shedding the old teeth, distinct from other osteichthyan dentitions. Actinopterygian teeth can be recognized by a cap of enameloid, while sarcopterygian teeth are only coated by enamel. An enameloid cap is also borne by the unicuspid larval teeth in some amphibians, but it is covered by enamel and eventually disappears in the bicuspid adult teeth. In early osteichthyans, old teeth are often not completely resorbed and shed, and the overlapping relationship of their remnants buried in the bone records the sequence of developmental events. Using synchrotron microtomography, this ontogenetic record of a coronoid tooth field of a Devonian stem actinopterygian is visualized in 3D. As a component of the inner dental arcade, the coronoid displays initial radial non-shedding tooth rows followed by radial shedding tooth rows that are later transformed into linear shedding tooth rows. The teeth are always added antero-labially and replaced labially to keep pace with the labial bone apposition and lingual bone remodeling, which causes the shift of the tooth competent zone. These provide a clue to the evolution of the radial non-shedding dentition with antero-labial tooth addition in lungfish. The tooth patterning process suggests that the superficial disorder of the tooth field is an epiphenomenon of the ever-changing local developing environment of each tooth bud: due to the retention of old tooth bases, a tooth position that has been replaced in place can at some point drift to a site between the adjacent tooth positions, splitting or merging, and then continue being replaced in situ. Primary teeth are capped by enameloid, but replacement teeth bear enamel crests without an enameloid cap. This demonstrates that the transition from enameloid capping to enamel coating through tooth replacement can happen in actinopterygians too, as one of the mechanisms for a dentition to change tooth shape. All these unexpected observations indicate that, during ontogeny, the states of dental characters, such as lingual/labial tooth initiation, linear/radial tooth rows, in situ/cross-position tooth replacement and enameloid/enamel, can be switched and the capacity to produce these characters can be suspended or reactivated; the tremendous dental diversity can thus be attributed to the manipulation in time and space of relatively few dental developmental processes.