Journal of Anatomy最新文献

Multiple sclerosis (MS) is a progressive neurological autoimmune disease characterized by neuroinflammation and immune dysfunction. Existing treatments primarily focus on managing symptoms, highlighting the need for preventive and curative approaches. Recent research suggests that the sympathetic nervous system, particularly through beta-2-adrenergic receptor (β₂-AR) signaling on T cells, may play a role in regulating MS-related autoimmune responses, offering a potential novel therapeutic target. This study investigated the presence of sympathetic nerves and their proximity to T cells in human deep cervical lymph nodes (DCLN), which are implicated in MS autoimmune responses. Cadaveric dissections and microscopic imaging were employed to examine the presence of sympathetic nerves, their proximity to T cells and whether T cells express β₂-ARs. Sympathetic nerves were observed in 108 of 141 DCLNs and were located in varying regions of the lymphoid tissue, including active immune sites where they were in proximity to β₂-AR–expressing T cells. The observations of this study support the notion of a neuroimmune link in human DCLNs, which could represent a promising treatment target in T-cell-driven autoimmune diseases of the central nervous system, including MS.

The development of the human midface is still partly unknown. Despite much research, some aspects of dimorphism and growth trajectories during childhood remain unclear, due to the complexity and interdependence of structures such as the sphenoid bone or the maxilla, although various analytical methods, such as anthropometric measurements, geometric morphometry, and surface registration techniques, have been put in place and continue to be optimized for a better understanding of this complex development. We therefore set out to develop a surface registration method without segmentation, through a MultiSlice Computed Tomography (MSCT) study of midface development in immature children aged 0 to 15 years. This study tested the feasibility of this method by creating mean shapes by sex and age, and producing colorimetric maps of intersex deformation within age and intrasex deformation between adjacent ages, in order to visualize the effects of growth and dimorphism on midface shape, independently of size. To ensure clarity of analysis, only results from individuals aged 3, 9, 11, and 15 years were reported, focusing on the maxillary arch, maxillary sinuses, and palate. The results reveal sex and age differences, observed through voxel contractions and dilations in the images. These deformations appear to be linked to dental eruptions and associated bone remodeling, which also lead to inferior displacement of the maxillary sinuses during growth. Furthermore, it was noted that these processes manifest themselves earlier in female individuals, while male individuals show more robust teeth and structures by the end of puberty. Finally, although the results obtained with this method are promising, further efforts are needed due to the many challenges encountered during the process, and will provide a better understanding of maxillary growth, enabling better prevention of pathologies linked to this zone, better diagnosis, and development of early treatments for these pathologies.

Irregular leading edge (LE) surfaces can increase the aerodynamic efficiency of airfoils in some situations, although the exact mechanism is debated. The current study assessed the aerodynamic effect of LE tubercles present on the pinna of the fast-flying bat species, Tadarida brasiliensis. Using micro-computed tomography (μCT) to build the pinna geometry and finite volume computational fluid dynamics (CFD), air flow was modeled over a static naturally shaped 3D tubercled pinna and an edited smoothed 3D pinna at various angles of attack (AoA) to assess the aerodynamics of pinna LE tubercles. Model results supported the hypothesis, with the tubercled pinna exhibiting marginally reduced drag at the AoAs leading up to stall and increased lift in the AoAs post stall. This increase in aerodynamic efficiency was due to the generation of streamwise vortices shed off the LE tubercles. These data add to the growing body of literature on naturally occurring LE tubercles and their role in aerodynamic efficiency.

The white matter of the spinal cord is essential for sensory and motor signaling, and its proper development is crucial for establishing functional neuronal circuits. However, the mechanisms underlying white matter formation remain incompletely understood. We hypothesized that the extracellular matrix, particularly laminins, plays a key role in this process. The spatiotemporal expression patterns of laminins during spinal cord white matter development have not been fully characterized. Here, we examined the distribution and function of laminins during spinal cord development. Laminin 332 localized to the marginal zone of the spinal cord at embryonic days 12 (E12) and 14 (E14), coinciding with periods of extensive axonal growth. Immunohistochemical analysis revealed an increase in glial fibrillary acidic protein (GFAP)-positive fibers in laminin 332-enriched regions. Laminin 332 promoted GFAP expression in astrocyte precursor cells, an effect attenuated by integrin α6β4 blockade, suggesting that laminin 332 signals through integrins to support astrocyte maturation. Our findings indicate that laminin 332 not only serves as a structural component of the extracellular matrix but also actively regulates glial differentiation during spinal cord development. Understanding the signaling pathways mediated by laminin 332 may inform therapeutic strategies aimed at enhancing spinal cord regeneration by modulating astrocyte behavior and promoting axonal growth.

The knee joint plays a critical role in tetrapod locomotion, yet its developmental trajectories and anatomical diversity remain underexplored outside of model taxa. Here, we examine knee joint development in three representative reptilian lineages, Phrynops hilarii (Testudines), Caiman latirostris (Crocodylia), and Columba livia (Aves), and compare them with adult knee morphology in two squamate species, Cercosaura parkerii and Hemidactylus mabouia. Using histological series spanning key developmental stages, we document patterns of ossification, meniscus formation, cartilage composition, and sesamoid presence. All taxa share delayed epiphyseal ossification and early ligament and meniscus differentiation. However, they differ in meniscal shape, tissue composition, tibial plateau morphology, and sesamoid expression. Notably, P. hilarii lacks a patella but seems to present both a fabella and a cyamella; C. latirostris and C. livia exhibit distinct patellar configurations, with C. livia displaying a multi-element patellar complex. Cartilage thickness and composition also vary, with thinner cartilage and a narrower interarticular zone observed in C. livia. Ancestral state reconstruction supports a single origin of the patella within Reptilia and highlights multiple instances of anatomical convergence. These findings underscore the functional diversity of the reptilian knee and provide a developmental framework for interpreting the evolution of limb joint morphology across tetrapods.

The uniqueness of human brain growth and development has been considered promising for its contribution to understanding the origins of the unique human cognitive abilities. Compared with that of chimpanzees, the human endocranium undergoes several characteristic shape changes immediately after birth, which has been termed “endocranial globularization.” However, how the brain structures and surrounding neurocranium interact with each other during early development in the context of brain–neurocranium integration remains to be investigated. We investigated shape and size changes in the human brain and endocranium during postnatal development using magnetic resonance imaging, and analyzed spatial constraints and interactions among subdivisions of the brain influencing endocranial morphology. Our results suggest that, during postnatal development, the relative size changes of supratentorial and infratentorial regions and the cranial base largely constrain brain and endocranial shape. Specifically, a disproportionate increase in the size of the infratentorial region (i.e., cerebellum plus brainstem) relative to the cranial base affects the infratentorial spatial packing constraint in neonates, causing inferoposterior expansion of the posterior cranial fossa and coronal reorientation of the petrous pyramid of the temporal bone without flattening the angle between the two sides of the tentorium cerebelli. The dramatic size increase of the infratentorial region relative to the cranial base immediately after birth is inferred to be characteristic of human development and should be compared with non-human primates and potentially applied to fossil cranial series to obtain more evolutionary insight into the human cognitive ability.

Vertebrates exhibit remarkable morphological diversity, with the head representing an exceptionally complex anatomical structure shaped by adaptations to feeding ecology, brain size, and sensory organ specialization. Proper fusion of facial prominences and the coordinated growth of the skull and brain are essential for normal craniofacial development in vertebrates, including humans. Disruptions in these processes, whether due to gene mutations or external factors, can result in craniofacial malformations. In this study, we examined two pathological embryos of the brown anole, Anolis sagrei (Iguania: Anolidae), exhibiting notable craniofacial anomalies, including brachycephaly, mandibular prognathism, bilateral palatal clefts, and ocular defects. Comparative 3D reconstructions based on histological serial sections of malformed and normal embryos of similar developmental stages revealed instances of craniosynostosis, the absence of certain endocranial elements, skull shape abnormalities, and asymmetries. Furthermore, a wide range of postcranial anomalies was identified, including syndactyly, missing or shortened digits, and tail abnormalities. To the best of our knowledge, these are the first documented cases of non-experimentally induced craniofacial malformations and limb syndactyly occurring within the same individuals in squamates and non-avian reptiles in general. This rare combination was observed in both malformed embryos. Given the striking morphological resemblance to human craniofacial disorders, particularly Apert syndrome, we hypothesize the involvement of a shared genetic mechanism in mammals and sauropsids that may trace back over 320 million years. However, without molecular data, this remains speculative. Nonetheless, growing evidence suggests that non-avian reptiles, particularly squamates, could be valuable models for studying human craniofacial disorders. While the adaptive significance of the malformations observed here remains uncertain, these cases may represent examples of “hopeful monsters,” offering valuable insights into the evolutionary processes that have shaped the distinctive vertebrate morphology of clades such as chameleons. Notably, several traits observed in the malformed anole embryos—including eyelid fusion, upper jaw shortening, syndactyly, and certain skeletal characteristics—appear to reflect features reminiscent of the peculiar chameleon phenotype.

Cover image: Compacted coarse cancellous bone, a tapestry of new growth on an old framework, and a metaphor for modern palaeohistology. See G. Funston et al., ‘Palaeohistology and life history of the early Palaeocene taeniodont Conoryctes comma (Mammalia: Eutheria)’, this issue.

The precuneus is a central hub of the human brain, and its morphology displays a noticeable individual variability. It is larger in humans than in other primates, and it is affected by atrophy and hypometabolism in the early stages of Alzheimer's disease (AD). In this study, we compare its general morphology in normal aging subjects and AD patients, considering its geometry through shape analysis, and the atrophy at its boundary by quantifying the intersulcal spacing. Results suggest that the AD sample displays a reduction of the inferior regions of the precuneus, namely those that fade into the posterior cingulate and retrosplenial cortex. During aging, sulcal spacing is pronounced at the superior and posterior regions, although in the AD sample the latter change is more marked. However, these differences are associated with a remarkable individual variation and a consistent overlap between group ranges. This study stresses further the differences between the dorsal and ventral regions of the precuneus. Beyond functional factors, the dorsal areas represent a region of scarce spatial constraints, whereas the ventral regions are embedded in a complex topological environment. This structural difference must be considered when investigating cortical morphology in both normal and pathological conditions.

The study of the connection between the teeth and the jaw is important for understanding the palaeobiology of vertebrates, but inconsistent terminology and incomplete sampling have made it difficult to assess the evolutionary significance of some of the related characters. Among archosauromorphs, tooth attachment in dinosaurs and crocodylians is nearly identical to that of mammals in featuring a ligamentous connection (gomphosis), whereas closely related forms appear to have teeth fused to the jaws (ankylosis), as in most other amniotes. Hence, studying tooth attachment of stem-archosaurs is pivotal to characterize the main shifts in tooth attachment seen in the lineage. Here, we analyze the tooth attachment of rhynchosaurs — a group of quadrupedal herbivorous archosauromorphs that played a key role as primary consumers in many Triassic communities. Their dentition consists of multiple rows of marginal teeth with posterolingual addition of teeth during growth, but their tooth attachment has not been documented in a modern context. Histological data from three rhynchosaur specimens from the Middle Triassic Manda Beds of Tanzania show that, although ankylosed, rhynchosaur teeth are surrounded by an extensive network of Sharpey’s fibers, layers of cementum, and well-defined zones of alveolar bone. What has been previously described as “spongy bone of attachment” in fact encompasses the same attachment tissues present in mammals, dinosaurs, and crocodylians, albeit completely mineralized in mature teeth. Analysis of different stages of tooth development shows that ankylosis occurs by the growth of alveolar bone towards the cellular cementum, which eventually mineralizes the soft ligament. This suggests that the tissues conflated as “bone of attachment”—alveolar bone, periodontal ligament, and cellular cementum—are homologous across Archosauromorpha. Our data add to a growing body of evidence that heterochronic changes to the timing and extents of mineralization, not convergent evolution to mammal-like attachment tissues, led to the independent evolution of gomphosis across many amniote lineages, including archosauromorphs.