Journal of Anatomy最新文献

Front cover:

Cover image: see A.B. Lawson and colleagues, ‘Variation in air sac morphology and postcranial skeletal pneumatization patterns in the African grey parrot (Psittacus erithacus)’, this issue.

The fovea, a pit in the retina, is crucial for high-acuity vision in humans and is found in the eyes of other vertebrates, including certain primates, birds, lizards, and fish. Despite its importance for vision, our understanding of the mechanisms involved in fovea development remains limited. Widely used ocular research models lack a foveated retina, and studies on fovea development are mostly limited to histological and molecular studies in primates. As a first step toward elucidating fovea development in nonprimate vertebrates, we present a detailed histological atlas of retina and fovea development in the bifoveated Anolis sagrei lizard, a novel reptile model for fovea research. We test the hypothesis that retinal remodeling, leading to fovea formation and photoreceptor cell packing, is related to asymmetric changes in eye shape. Our findings show that anole retina development follows the typical spatiotemporal patterning observed in most vertebrates: retinal neurogenesis starts in the central retina, progresses through the temporal retina, and finishes in the nasal retina. However, the areas destined to become the central or temporal fovea differentiate earlier than the rest of the retina. We observe dynamic changes in retinal thickness during ocular elongation and retraction-thinning during elongation and thickening during retraction. Additionally, a transient localized thickening of the ganglion cell layer occurs in the temporal fovea region just before pit formation. Our data indicate that anole retina development is similar to that of humans, including the onset and progression of retinal neurogenesis, followed by changes in ocular shape and retinal remodeling leading to pit formation. We propose that anoles are an excellent model system for fovea development research.

Diabetes mellitus type 2 (DMT2) promotes Achilles tendon (AS) degeneration and exercise could modulate features of DMT2. Hence, this study investigated whether tenocytes of non DMT2 and DMT2 rats respond differently to normo- (NG) and hyperglycemic (HG) conditions in the presence of tumor necrosis factor (TNF)α or cyclic stretch. AS tenocytes, isolated from DMT2 (fa/fa) or non DMT2 (lean, fa/+) adult Zucker Diabetic Fatty (ZDF) rats, were treated with 10 ng/mL TNFα either under NG or HG conditions (1 g/L vs. 4.5 g/L glucose) and were exposed to cyclic stretch (14%, 0.3 Hz, 48 h). Tenocyte survival, metabolic activity, gene and/or protein expression of tendon extracellular matrix component collagen type 1, alpha smooth muscle actin (αSMA, Acta2), the stress defense enzyme heme oxygenase-1 (Hmox1) as well as suppressors of cytokine signaling (Socs)1 and Socs3 were analyzed. Tenocyte vitality remained high, but metabolic activity was slightly impaired by HG conditions irrespectively of cell origin. Collagen type 1 alpha protein and gene expression was suppressed by TNFα, but only in cells of non DMT2 animals in NG culture medium. Higher amounts of αSMA were visualized in tendons/tenocytes of diabetic rats or those exposed to TNFα. Cyclic stretch caused cell alignment in zero stretch direction. In addition, it led to a significant reduction of cell perimeters, particularly in cells of DMT2 donor rats under HG conditions. Hmox1, Socs1 and Socs3 were induced by HG, but only in tenocytes of diabetic rats (4 h). Stretch induced significantly Hmox1 transcriptional activity under NG conditions and Socs3 under HG conditions especially in tenocytes of DMT2 rats. The response of tenocytes to TNFα and cyclic stretch depends on glucose supply and origin suggesting their irreversible impairment by DMT2.

The evolutionary conservation of the building plan of the heart suggests this organ is under substantial form-function constraints. Its form varies to such a degree, however, that it questions whether we understand the form-function relations of the heart. A previously published image of the heart of the sunfish (Mola mola, Tetraodontiformes) indicates the presence of an exceptionally simple topology of the chambers. Here, we describe the gross morphology of the sunfish heart (N = 7) because, we assess, this expands the known spectrum of cardiac form that is compatible with function. The usual teleost piscine compartments were present, guarded by valved junctions: sinus venosus, atrium, ventricle, and bulbus arteriosus. Especially, the ventricle was much displaced ventrally and the atrium was dorso-ventrally elongate. The ventricular central cavity exhibited a simple 90-degree curve, or a-quarter circle, and opened into an almost vertical bulbus arteriosus. Overall, the normal piscine S-topology of the cardiac chambers (when seen from the left) appeared distorted to a simpler J-shape. When compared to other fish, including a tetraodontiform boxfish, these highly unusual characters appeared to have evolved recently. The distantly related spotted tinselfish (Xenolepidichthys dalgleishi) resembles sunfish in shape, its heart is almost J-shaped, but the ventricle was sac-like and typically piscine. Surprisingly, the ventricular wall had a comparatively high proportion of compact myocardium, approximately 34%. The relative mass of the sunfish heart was typically piscine, approximately 0.08% of body mass. In conclusion, the sunfish heart may be the least curved cardiac structure described for any fully formed vertebrate.

During the Late Permian, saber-toothed gorgonopsian therapsids were the dominant terrestrial predators, playing crucial roles as apex predators alongside therocephalian therapsids within Permian terrestrial ecosystems. The entire gorgonopsian clade went extinct during the Permo-Triassic mass extinction, leaving other therapsids to continue into the Triassic. Gorgonopsians have not been well studied, particularly in terms of their growth patterns, with only a few genera having undergone osteohistological analysis. In this study, I present a thorough osteohistological examination of the most extensive collection of gorgonopsian specimens to date, spanning a diverse range of limb bones sourced from various species. The osteohistological analysis of gorgonopsian specimens reveals a trend of rapid growth characterized by a highly vascularized woven-parallel complex. The abundance of growth marks and variable zone widths suggests a growth trajectory that could indicate longer lifespans and slower growth rates when compared to Early Triassic therapsids. The high vascularity, coupled with the observed growth patterns, implies that gorgonopsians experienced rapid growth during favorable conditions. However, the multiple growth marks indicate that they likely had the capacity for longer lifespans and more gradual maturation than their Early Triassic counterparts. Additionally, their ability to reach later ontogenetic stages supports the hypothesis that favorable environmental conditions facilitated larger body sizes. In contrast, Early Triassic therapsids primarily consisted of juveniles or individuals who reached reproductive maturity within a year, likely indicative of harsher conditions that contributed to higher mortality rates at younger ages. The onset of decreased growth rates, usually indicative of reproductive maturity, occurred later in gorgonopsians compared to Early Triassic therapsids and may have contributed to their decline, as the heightened juvenile mortality rates during the PTME would have limited the gorgonopsians' ability to reproduce effectively.

Inflammatory bowel disease (IBD) encompasses Crohn's disease (CD) and ulcerative colitis (UC), is a major health problem on a global scale and its treatment is unsatisfactory. We aimed to investigate the effects of transauricular vagal nerve stimulation (tVNS) on inflammation in rats with IBD induced by trinitrobenzene sulfonic acid (TNBS). A total of 36 adult female Sprague–Dawley rats were given TNBS, or vehicle, and tVNS, or sham, every other day for 30 min for 10 days. Postmortem macroscopic and microscopic colon morphology were evaluated by histological staining. Additionally, IL-1β, IL-6, IL-10, and TNF-α cytokine levels in the colon and the brain were evaluated by immunohistochemistry and western blotting analysis. TNBS induced epithelial damage, inflammation, ulceration, and thickened mucosal layer in the colonic tissues. Administration of tVNS significantly ameliorated the severity of TNBS-induced tissue damage and inflammatory response. TNBS also alters pro-inflammatory and anti-inflammatory balance in the brain tissue. TVNS application significantly suppressed the protein levels of pro-inflammatory cytokines, namely IL-1β, IL-6, and TNF- α while augmenting the level of anti-inflammatory cytokine IL-10 in the colonic and the brain tissue. We have shown that TNBS-mediated colonic inflammation and tissue damage are associated with neuroinflammatory responses in the brain tissue. Also demonstrated for the first time that neuroinflammatory response in the gut-brain axis is suppressed by tVNS in the IBD model. Non-invasive tVNS stands out as a new potential treatment option for types of IBD.

The anatomy of molar teeth is important both functionally for chewing food and in evolutionary studies as a well-preserved species marker in the fossil record. Molar teeth begin to develop their characteristic biting-surface shape of cusps (peaks) and sulci (valleys) at the bell stage, when corresponding folds in the dental epithelium become apparent. Theories about the developmental mechanisms of cusp and sulcus morphogenesis have hitherto largely focused on the non-proliferating nature of the secondary enamel knots (EKs) at the cusp tips. EKs have been thought to direct cusp/sulcus formation by stimulating proliferative growth of the surrounding epithelium which, being confined within a capsule of condensed mesenchyme, bends by mechanical buckling. Here we show, using explant inhibition and cut-and-recoil experiments, that cap-to-bell morphogenesis is largely proliferation-independent (sulcus sharpening entirely so) and that tension in the mesenchyme of the dental papilla, immediately sub-adjacent to the cusps, rather than compression by the mesenchyme surrounding the whole structure, is what holds the structure in shape. Fine mapping of the degree of condensation shows that it is highest in the mesenchyme of the dental papilla and becomes progressively more focused to the cusp regions, consistent with a key role in cusp shaping. Together these findings overturn the prevailing models of molar morphogenesis, including both cusp and sulcus formation.

Understanding normal structural and functional anatomy is critical for health professionals across various fields such as medicine, veterinary, and dental courses. The landscape of anatomical education has evolved tremendously due to several challenges and advancements in blended learning approaches, which have led to the adoption of the use of high-fidelity 3D digital models in anatomical education. Cost-effective methods such as photogrammetry, which creates digital 3D models from aligning 2D photographs, provide a viable alternative to expensive imaging techniques (i.e. computed tomography and magnetic resonance imaging) whilst maintaining photorealism and serving multiple purposes, including surgical planning and research. This study outlines a comprehensive workflow for producing realistic 3D digital models from embalmed veterinary specimens. The process begins with the preservation of specimens using the modified-WhitWell (WhitWell-Liverpool) embalming protocol, which ensures optimal tissue rigidity and improved colour enhancement, facilitating easier manipulation and better photogrammetry outcomes. Once embalmed, specimens are photographed to create digital 3D models using photogrammetry. Briefly, all images are processed to generate a sparse point cloud, which is then rendered into a 3D mesh. The mesh undergoes decimation and smoothing to reduce computational load, and a texture is applied to create a lifelike model. Additional colour enhancements and adjustments are made using digital tools to restore the natural appearance of the specimens. The 3D models are stored on a cloud repository and integrated into the University of Liverpool's Virtual Learning Environment, providing continuous, remote access to high-quality anatomical resources. The switch to embalmed specimens during the COVID-19 pandemic allowed for longer-term use and detailed dissections, enhancing the quality of digital models. Fresh specimens, though naturally coloured, are less stable for photogrammetry, making embalmed specimens preferable for accurate 3D modelling. Our method ensures embalmed specimens are rigid enough for precise modelling while allowing texture adjustments to enhance digital representation. This approach has improved logistical efficiency, educational delivery, and specimen quality. Innovative embalming techniques and advanced photogrammetry have the power to revolutionise anatomical education with the creation of a vast digital library accessible online to students at any time. This approach paves the way for integrating digital 3D models into immersive environments and assessing their impact on learning outcomes.