Anatomical Record最新文献

Glisson's sheath is the connective tissue ensheathing the portal vein, hepatic artery, and bile duct within the liver. Although the connective tissue surrounding the liver surface is known as Glisson's capsule, its structure and function are poorly understood. In the present study, we analyzed mouse, rat, rabbit, feline, canine, monkey, porcine, bovine, and equine livers by histochemistry and immunohistochemistry analysis of α-smooth muscle actin, keratin 19, and podoplanin and examined how the structure of the Glisson's capsule is conserved and differs among the nine species. Glisson's capsule tended to thicken as the animal's body size increased. Among the nine mammalian species, bile ducts were observed adjacent to the connective tissue of Glisson's capsule in adult monkey, porcine, bovine, and equine livers without association with portal veins. Fetal monkey and porcine livers exhibited thin Glisson's capsules without bile duct development. The hepatic artery develops in the Glisson's capsule in adult canine, monkey, porcine, bovine, and equine livers without association with the bile ducts and portal veins. Similar to the human liver, the livers of adult monkeys develop lymphatic vessels beneath the liver surface. The present study reveals for the first time that the structure of the Glisson's capsule differs considerably between small (mouse, rat, rabbit, and cat) and large (monkey, pig, cattle, and horse) animals and that the dog exhibits an intermediate structure between the two groups.

Computed tomography (CT) enables rapid imaging of large-scale studies of bone, but those datasets typically require manual segmentation, which is time-consuming and prone to error. Convolutional neural networks (CNNs) offer an automated solution, achieving superior performance on image data. In this methodology-focused paper, we used CNNs to train segmentation models from scratch on 2D and 3D patches from micro-CT scans of otter long bones. These new models, collectively called BONe (Bone One-shot Network), aimed to be fast and accurate, and we expected enhanced results from 3D training due to better spatial context. Contrary to expectations, 2D models performed slightly better than 3D models in labeling details such as thin trabecular bone. Although lacking in some detail, 3D models appeared to generalize better and predict smoother internal surfaces than 2D models. However, the massive computational costs of 3D models limit their scalability and practicality, leading us to recommend 2D models for bone segmentation. BONe models showed potential for broader applications with variation in performance across species and scan quality. Notably, BONe models demonstrated promising results on skull segmentation, suggesting their potential utility beyond long bones with further refinement and fine-tuning.

The Shishugou Formation of the Middle to Late Jurassic in Xinjiang, China, has produced abundant tetrapod fossils including dinosaurs and tritylodontids. Bienotheroides is a genus of highly specialized tritylodontids, characterized by a short and wide snout, ventrally expanded zygomatic process, strongly reduced maxilla, short and flat basisphenoid, and maxillary teeth cusp formula 2-3-3. Here, we report a new tritylodontid, Bienotheroides wucaiensis sp. nov. from the lower Upper Jurassic level of the formation at Wucaiwan, Xinjiang, Northwest China, represented by a well-preserved cranium and associated postcranial skeleton. Micro-computed tomography and 3D reconstruction reveal the medial view of the cranial structure and the replacement upper incisors, providing new anatomical information of Bienotheroides. The absence of a septomaxilla in B. wucaiensis reveals the homoplastic evolution of this feature within tritylodontids, as it remains in basal mammaliaforms but is lost in later descendants.

In January 2021, Kurt Albertine, PhD, stepped down as the Editor of The Anatomical Record after 15 years of dedicated service. As Editor-In-Chief, he oversaw incredible growth, expanded scope, and increased impact of the journal. At the same time, he directed an active research lab in neonatal pulmonary biology at the University of Utah, with an exceptional track record of mentoring students, fellows, clinicians, and junior faculty. This special issue of The Anatomical Record honors Kurt's contributions to the journal, as well as to the fields of respiratory anatomy, physiology, and neonatology. Several of the invited papers were contributed by Kurt's collaborators and former trainees who cover topics related to neonatal lamb development, bronchopulmonary dysplasia, postnatal lung pathology, respiratory physiology, and the relationship of anatomy to function. Additional papers relating to Kurt's passion for dinosaur anatomy and human embryonic anatomy based on the Kyoto Collection of Human Embryos and Fetuses. Kurt's tireless enthusiasm for the journal and devotion to the field are reflected in the papers in this special issue in his honor. His tenure at the journal was transformative and provided a foundation for continued growth and impact in anatomical sciences research from dinosaurs to clinical applications in humans. We celebrate Kurt's accomplishments and broader impact on anatomical sciences in this Special Issue of The Anatomical Record.

The Weberian apparatus is a hearing specialization unique to the otophysan fishes, and an unexpected degree of morphological variation exists in species of the Noturus catfishes. Our aim in this study is to investigate relationships between morphological variations and ecology that may drive this variation. Sampling 48 specimens representing 25 species, we investigated morphological diversity and accounted for ecological variables using landmark-based 3D geometric morphometrics and x-ray-based computed tomography (CT) images. We tested five ecological variables using three landmark sets in three focused regions: the tripus, scaphium, and overall shape of the peripheral structures including the complex vertebra. We performed phylogenetic signal tests, and phylogenetic influence is not significant within Noturus in any of the three regions. Among the tested ecological variables, stream velocity and coloration (a proxy for substrate) were found to be significantly associated with the morphology of the tripus and scaphium, the first and the last ossicles of the sound transmitting chain. This eco-morphology connection may be mediated through stream velocity's dominant role in defining the soundscape of aquatic environments and substrate material properties contributing to which sounds are produced and propagated. We conclude that Noturus catfishes could be acoustically adapted to their microhabitats.

Pangolins are the most heavily trafficked mammals in the world, largely because of the high demand for their keratinous scales from the traditional Chinese medicine market. While seizures of pangolin material are largely composed of isolated scales, efficient approaches to reach species-level identification are missing. This mostly originates from the lack of comparative studies on the shape of pangolin scales, resulting in knowledge gaps on the imbricated effects of serial, ontogenetic, and evolutionary variations. Using a large sample of micro-CT scan data, we performed the first quantitative 3D analysis of scale shape variation among the eight species of extant pangolins. Our geometric morphometric approach suggests that pangolins grossly share similar trends of serial variation, with scale shape and size being similarly distinct across the different body regions. Relative elongation is by far the main component of scale shape variation at the intraspecific level, although degree of asymmetry and shape of scale bed area also allow distinction among different body areas, especially in adults. At the evolutionary level, Phataginus is the most distinctive genus, with Pseudacteon tricuspis having the most elongated scales overall. Scales of the back (dorsum) appear to be the best discriminator between species, providing one of the few scale shape differences recorded between the genera Smutsia and Manis. Our results provide an unprecedented, upstream understanding of broad differentiation patterns across the scaled body of pangolins. Together with other yet-to-be-explored morphological traits (e.g., scale size, ornamentation, and thickness), scale shape could provide a valuable matrix of information for forensic applications.

Hypercanines, or hypertrophied canines, are observed in a wide range of both extinct and extant synapsids. In non-mammaliaform cynodonts, the Permo-Triassic forerunners of mammals, long canines are not uncommon, appearing in several unrelated taxa within the clade. Among them is Trucidocynodon riograndensis, a carnivorous ecteniniid cynodont from the Late Triassic of Brazil, which exhibits a specialized dentition, including spear-shaped incisors, very long and narrow canines, and sectorial postcanines with distally oriented cusps, all of which have finely serrated margins. Recent synchrotron X-ray micro-computed tomography of a large specimen (CAPPA/UFSM 0029; Várzea do Agudo site, Brazil) provides new insights into its lower jaw and dentition, as well as offers the first digital endocast of an ecteniniid. Our study reveals the presence of (i) putatively opened-root canines in the adult stage and the possible presence of unresorbed remnant of an old canine, which may indicate that the specimen stopped replacing its canines; (ii) lower canines that are longer than the upper canines and, in occlusion, were kept inside deep paracanine fossae that perforated the dorsal surface of the rostrum; (iii) a diastema between the incisors and lower canine, which is absent in the holotype; (iv) advanced brain structures, such as the absence of a pineal body, presence of cerebral hemispheres divided by the interhemispheric sulcus and expanded laterally, and a higher encephalization quotient than non-mammaliaform prozostrodonts, reflecting the homoplastic evolution of relative brain sizes observed in Triassic cynodont lineages. Finally, the abundance of carnivorous and omnivorous species at the Várzea do Agudo site, where the specimen was found-including the archosauriforms Dynamosuchus collisensis and Stenoscelida aurantiacus-suggests a diverse predator guild that warrants further investigation from a paleoecological perspective.

The pygmy sperm whale (Kogia breviceps) possesses an exocrine gland associated with its false gill slit pigmentation pattern. The cervical gill slit gland is a compound tubuloalveolar gland that produces a holocrine secretion and displays maturational changes in size and secretory histology. While the morphology of the cervical gill slit gland has been described in detail, to date, the chemical composition of its secretion remains uncharacterized. This study used histochemical staining techniques and quantitative lipid analysis to identify and characterize the constituents expressed in the secretory cells and secretion of the cervical gill slit gland. Results demonstrate that the secretion, like those of terrestrial artiodactyls that function in chemical communication, includes a complex mixture of carbohydrates, proteins, and lipids. Differences in staining intensity across germinal and secretory epithelial layers demonstrate differential expression, or maturation, of mucins and proteins. Additionally, a highly unusual and primary constituent of the secretion is uric acid. Uric acid was identified within the secretion using histochemical stains and polarized light imaging, and chemically verified using scanning electron microscopy with energy dispersive spectrometry. While uric acid is not a common constituent of mammalian exocrine glands, urate-based compounds are abundant in the secretions of marine organisms used in chemical communication. Thus, uric acid may contribute to the chemical message produced by K. breviceps in its marine environment. We hypothesize that the chemical signals produced by the gill slit gland may be shared at close-range by conspecifics, and that the mode of sensory reception is likely gustation.

Nothronychus graffami was a large therizinosaur represented by a single well-preserved individual from the Turonian Tropic Shale of southern Utah. It is characterized by an enlarged abdomen, small tail, and an extensively pneumatized axial skeleton, and is frequently regarded as herbivorous. Given the overall tail reduction and the development of a wide fused synsacrum with widely spaced acetabulae, it is reconstructed with an anteriorly rotated femur and a displaced resting ground reaction force anterior to the center of mass. The axis of the ground reaction force would shift laterally during locomotion to maintain stability as observed in extant broad abdomened neornitheans. A waddling gait is inferred for Nothronychus. This pattern is significantly different than in Falcarius, a basal therizinosaurian, where a plesiomorphic narrow abdomen, narrowly spaced acetabulae, and altiliac ilium are observed. Falcarius was capable of a more cursorial gait than derived therizinosaurs. In contrast to Nothronychus, Falcarius was probably at least omnivorous to carnivorous, so herbivory almost certainly evolved within the therizinosaur lineage. Following previous work on Tyrannosaurus and Coelophysis, moment arms were computed for Nothronychus for major muscles spanning the hip, knee, and ankle. A ball-and-socket joint is present at the hip, so three-dimensional movement was considered possible there. The knee and ankle were represented by two-dimensional hinge joints. Some muscles altered their function as the pubis shifted from a propubic orientation to an opisthopubic one. These included flexion to extension and the addition of increased abduction/adduction in the affected muscles. The results supported convergence with an avian locomotor model, such as reduction in M. caudofemoralis longus.