Back

The Anatomical Record

Wiley

Preprints posted in the last 90 days, ranked by how well they match The Anatomical Record's content profile, based on 13 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.

1
Specializations in Tail Anatomy of the Lesser Egyptian Jerboa (Jaculus jaculus) Compared with the Mouse and Rat

Miyamae, J. A.; Moore, T. Y.

2026-06-23 zoology 10.64898/2026.06.21.733634 medRxiv
Top 0.1%
12.5%
Show abstract

Mammal tails have long been recognized for their diversity of morphological form and function, however, there remains a substantial gap between the motivation to understand and emulate the various performance functions of the tail and what is known about tail anatomy. In this study, we were motivated to discover the anatomical foundations of the fast, whipping motions of the tail of the lesser Egyptian jerboa (Jaculus jaculus), which may aid in the quick changes of direction as the animal escapes from predators using ricochetal bipedal hopping. We employed microCT scans, dissections, and museum data to describe the musculoskeletal anatomy of the jerboa in comparison with the laboratory mouse (Mus musculus) and rat (Rattus norvegicus). While many aspects of tail anatomy are conserved across these species, the jerboa does possess unique characteristics such as an extremely long tail arising from caudal vertebral elongation, development of extensive dorsal musculature differentiated into lateral and medial components to increase points of skeletal attachment, and a novel anatomical feature - the bi-lobed cranial transverse process - which serves as a supernumerary dorsal tendon attachment site and possible brace to protect the ventral tendons and intrinsic muscles for a section of caudal vertebrae which likely experiences high mechanical stress.

2
Age-related morphological changes in the C57BL/6J mouse calvaria: implications for stereotaxic neurosurgery

Knight, Z. A.; Jang, H.

2026-04-28 neuroscience 10.64898/2026.04.24.720718 medRxiv
Top 0.1%
5.6%
Show abstract

The mouse skull serves as the coordinate framework for stereotaxic neurosurgery, yet whether aging alters surgically critical calvarial geometry has not been examined. We measured three parameters in large cohorts of young (2-3 months) and aged (23-30 months) male and female C57BL/6J mice: bregma-lambda distance and the dorsoventral depth at rostral-lateral (X = {+/-} 2.5 mm, Y = 0) and caudal-lateral (X = {+/-} 2.5 mm, Y = -0.65 mm) calvarial sites. Bregma-lambda distance was significantly reduced with aging in both sexes. Similarly, the rostral-lateral calvaria showed age-related flattening in both male and female mice. The more caudal-lateral site showed smaller but significant age-related flattening, with males exhibiting significantly greater reductions than females. Aging increased caudal-lateral shape variability while reducing bregma-lambda distance variability in males. On the contrary, aging reduced rostral-lateral shape variability in females. These findings demonstrate that the mouse skull undergoes significant, spatially non-uniform, and sexually dimorphic remodeling into old age, where skull shrinks along the midline and flattens more significantly at the rostral than caudal plane. Stereotaxic protocols designed for young adult mice may systematically misestimate skull geometry in aged animals. Age-stratified reference data should be incorporated into stereotaxic practice for aged rodent models.

3
Peripheral anatomy of the dolphin ear and associated nervous structures: insights from macroscopic dissection, DICE-{micro}CT, histology, and confocal microscopy

De Vreese, S.; Graïc, J.-M.; Mazzariol, S.; Huggenberger, S.; Fogli, M.; Luzzati, F.; Corona, C.; Favole, A.; Cerda-Domenech, M.; Frigola, J.; Andre, M.

2026-05-19 neuroscience 10.64898/2026.05.15.725593 medRxiv
Top 0.1%
3.3%
Show abstract

The peripheral auditory system of dolphins comprises specialised bony, fatty, vascular, and neural structures adapted for underwater hearing and diving physiology. These include the external ear canal, acoustic fat bodies, sinuses, and associated neurovascular networks, which together support sound conduction, protection, and possibly sensory functions. Despite advances in gross anatomical description, the detailed integration of these tissues, particularly the innervation, neurovascular organisation, and their functional implications, remains poorly understood. Previous studies have described the presence of sensory nerve formations and vascular plexuses, but their arrangement, connectivity, and relation to each other are unresolved. Here, we combine macroscopic dissection, DICE-{micro}CT, histology, and high-resolution confocal microscopy to characterise several neurovascular and sensory components of the dolphin peripheral auditory system in several delphinid species. Macroscopic dissection and DICE-{micro}CT revealed the traditional acoustic fat body distribution with detailed morphology of the posterolateral extension that is not well-known. The cranial nerve distribution, and specifically the mandibular nerve branching patterns, are described in detail. Confocal microscopy uncovered a stratified neurovascular plexus around the external ear canal with a complex sensory system comprising lamellar corpuscles, Merkel cell-neurite complexes, and intraepithelial nerve fibres. Notably, the lamellar corpuscles formed a continuous, three-dimensional neural network with frequent merging and splitting of axonal bundles, shared perineuria, and vascular integration, features not observed in previous studies. Our findings demonstrate that the dolphin external ear canal and surrounding structures form a sophisticated, multimodal somatosensory organ, integrating structural, vascular, and neural specialisations likely adapted for proprioceptive mechanosensation in the aquatic environment. This study provides insights into the integration of the various components of the peripheral hearing apparatus. Future studies integrating anatomical, electrophysiological, and biomechanical approaches are needed to fully elucidate these adaptations.

4
A new skeleton of the gorgonopsian Aelurognathus tigriceps from the Daptocephalus Assemblage Zone (Karoo Basin, South Africa) with novel insights into the pelvic girdle, hind limbs, and tail

Pevsner, S. K.; Benson, R. B. J.; Kammerer, C. F.

2026-05-30 paleontology 10.64898/2026.05.27.727204 medRxiv
Top 0.1%
3.2%
Show abstract

Gorgonopsian therapsids represent a transitional condition in the evolution of synapsid locomotion and postcranial structure. Most descriptions of gorgonopsians have focused on cranial material, however, limiting their usefulness for informing patterns of postcranial evolution on the mammal stem. While some recent work has begun to focus on postcrania, especially the pectoral girdle and forelimbs, comparatively little data are available on the pelvic girdle, hind limbs and tail. We report a new specimen of the late Permian gorgonopsian Aelurognathus tigriceps comprising a partial skull and well-preserved postcranial skeleton, including the near-complete series of dorsal vertebrae and ribs, complete pelvic girdle, hind limbs, feet, and a nearly complete tail. The tail is longer than any other published gorgonopsian. The new material presented here provides an opportunity to better establish broader patterns of morphology in the gorgonopsian postcranial skeleton.

5
Reverse gingival venipuncture: a refined technique for serial blood collection in small rodents

Luapan, J.; Johnson, H.; Seiberlich, M.; Brayton, C. A.; Jimenez, I. A.

2026-04-28 zoology 10.64898/2026.04.24.720739 medRxiv
Top 0.1%
2.6%
Show abstract

ObjectiveTo assess the safety, efficacy, and repeatability of a novel blood collection technique, percutaneous reverse gingival venipuncture (RGV), across multiple rodent species, and to characterize the associated anatomy through dissection and histopathology. MethodsSuccess rate and complications of RGV were evaluated at a private practice between December 2024 and September 2025 in client-owned chinchillas (Chinchilla lanigera) (n=102), guinea pigs (Cavia porcellus) (n=78), Syrian hamsters (Mesocricetus auratus) (n=32), dwarf hamsters (Phodopus campbelli and P. sungorus) (n=4), squirrels (Callosciurus erythraeus, C. finlaysonii) (n=7), prairie dogs (Cynomys ludovicianus) (n=2), a capybara (Hydrochoerus hydrochaeris) (n=1) and a Patagonian mara (Dolichotis patagonum) (n=1). An experimental study was conducted in laboratory rats (Rattus norvegicus) (n=5), Chinese hamsters (Cricetulus griseus) (n=12), and chinchillas (n=11) from February 2026 to March 2026 to evaluate RGV success rate, serial hematology, and histopathology. ResultsThe success rate of RGV was 100% in most rodent species, but was lower in guinea pigs (44.87%, n=78) and chinchillas (64.60%, n=113). No animals experienced clinical complications. No significant changes in serial hematology were appreciated in Chinese hamsters (n=6) on days 0, 7, and 14. Histopathology did not reveal any complications. ConclusionsRGV in anesthetized rodents is safe, effective, minimally invasive, and repeatable, yielding clinically relevant blood volumes with precise control and minimal risks. Clinical RelevanceRGV may facilitate more routine hematology and chemistry analysis in rodents by veterinary practitioners, with few risks and complications. In research settings, RGV may improve animal welfare and contribute to refinement and reduction.

6
Mapping feather vane structure across the avian wing: spatial variation, asymmetry, and the effect of flight style

Osvath, G.; David, D.-C.; Vargancsik, D.; Nagy, L. J.; Andrea Feher, A.; Zsolt Kovacs, Z.; Lendvai, A. Z.; Vincze, O.; Nudds, R. L.; Vagasi, C. I.; Pap, P. L.

2026-06-11 zoology 10.64898/2026.06.08.730791 medRxiv
Top 0.1%
2.1%
Show abstract

Flight feather vanes are the primary aerodynamic surface of the avian wing. Because loading varies across the wing, vane macrostructure should co-vary with local mechanical demands, yet comparative data on how barb and barbule traits change among remiges and between vane surfaces remain scarce. We quantified barb density, barbule density, barb angle, barb length, and vane width on both vanes at three measurement positions along the rachis of all remiges in four species with contrasting flight modes (white stork, common buzzard, house sparrow, pygmy cormorant), generating over 40,000 measurements across 15 response variables from 992 feathers of 41 individuals. Two complementary generalised additive models characterised variation along the spanwise, inter-vane, and longitudinal axes, and compared outer primaries, inner primaries, and secondaries as functional wing regions. Feather macrostructure varied along all three axes and outer primaries represent the most distinctive region, with lower leading-vane barb density, reduced barb angles, and vane width asymmetry two to three times higher than in inner primaries or secondaries. House sparrow exhibited the densest vane architecture and the highest vane width asymmetry, whereas the low wing-beat frequency species showed complex nonlinear spanwise patterns undetectable by single-feather sampling. Pygmy cormorant barbule density was 39-53% lower than in all other species, matching its wettable plumage strategy. Longitudinal gradients in barb density and barb angle (22-31% decline) were conserved across species. The avian wing is thus functionally regionalised at the macrostructural level, with vane architecture reflecting both aerodynamic and ecological pressures. Summary statementFine-scale vane measurements across all remiges in four species show macrostructural regionalisation of the avian wing, with outer primaries showing the most distinctive vane architecture.

7
Scaling and ecomorphology of lagomorph body shape and appendicular skeleton

Huizenga, C.; Brice, N.; Law, C. J.

2026-05-12 evolutionary biology 10.64898/2026.05.07.723560 medRxiv
Top 0.1%
1.8%
Show abstract

The diversity of body shapes is one of the most prominent features of phenotypic variation in mammals. Yet, mammalian body shapes are poorly quantified and the underlying components contributing to its diversity as well as its relationship to other components of the skeleton are rarely tested. Here, we use lagomorphs (hares, rabbits and pikas) as a model system to (1) investigate which components of the skeleton contributed the most to body shape diversity, (2) examine the relationships between body shape and relative limb lengths, and (3) test how body size, ecotype, burrowing behavior, and locomotor mode influenced variation in lagomorph body shape and appendicular morphology. We quantified the body shape and functional proxies of the appendicular skeleton in 40 lagomorph species from osteological specimens held at museum collections. Using phylogenetic comparative methods, we found the relative length of the ribs and elongation or shortening of the thoracic and lumbar regions contributed the most to body shape evolution across lagomorphs. Second, we found that only leporids (hares and rabbits) exhibited a significant relationship between limb length and body shape, where more elongate species exhibit relatively shorter forelimbs and hindlimbs. Lastly, we found that models incorporating body size were the best predictors of lagomorph body shape and the majority of the appendicular traits, whereas models incorporating burrowing behavior and locomotor mode were largely poor fits. Broadly, these results indicate that larger lagomorphs tend to exhibit more robust body shapes with longer, more gracile forelimbs, whereas smaller lagomorphs tend to exhibit more elongate body shapes with shorter, more robust forelimbs. Overall, this work contributes to the growing understanding of mammalian body shape evolution and demonstrates the importance of not omitting body size in ecomorphological analyses.

8
Biomechanics of the extremely elongated neck of the Triassic archosauromorph Tanystropheus

Rytel, A.; van Bijlert, P. A.; Lautenschlager, S.; Spiekman, S. N. F.; Talanda, M.; Sulej, T.

2026-07-02 paleontology 10.64898/2026.06.28.735087 medRxiv
Top 0.1%
1.7%
Show abstract

Extremely elongate necks have convergently evolved in several amniote lineages, including both aquatic and terrestrial forms (Fig. 1). The development of such a feature brings with it advantages in obtaining food items, but also biomechanical challenges, such as flexibility, stability, lift, and inertia. In Tanystropheus, a particularly long-necked Triassic archosauromorph, the neck is composed of only 13, mostly extraordinarily elongated and slender cervical vertebrae and accompanying rod-like, overlapping ribs, making it arguably the most extreme example of neck elongation in tetrapod evolution (Fig. 1;1-6). Understanding the function of this remarkable neck provides insights into the limits of neck elongation in amniotes and the evolution of morphological novelties in Triassic reptiles. Here we present the first quantitative biomechanical analysis of the Tanystropheus neck using a digital model based on three-dimensionally preserved bones. We assessed its range of motion (ROM) and performed finite element analysis (FEA) on the individual cervical ribs and the neck model in different configurations. Our results indicate that the neck of Tanystropheus was not extremely stiff, as previously postulated, and the ribs likely did not impair its movements. They transferred tensile forces towards the base of the neck, similar to what hypothesized for sauropods7. This study elucidates the bauplan of an extremely specialized animal and brings us closer to understanding the patterns of achieving neck elongation in vertebrates.

9
Parental transport induces a dormant state while maintaining oxytocin recruitment in poison frog tadpoles

Antunes, D. F.; Liu, Z.; Ringler, E.

2026-06-22 neuroscience 10.64898/2026.06.16.732608 medRxiv
Top 0.1%
1.5%
Show abstract

Parental care can have pervasive effects on offsprings neurodevelopment. Parent-offspring interactions are often modulated by the neuropeptide oxytocin, which is responsible for the development of social bonds. The development of the oxytocinergic system is dependent on the quality of parental care during the post-natal phase. However, it is yet unknown how post-natal direct interactions can influence the development of the oxytocinergic pathway. Here we tested how an obligate parental care behaviour, tadpole transport in poison frogs, influences the development of the oxytocinergic pathway. To this end, we quantified whole brain expression of oxytocin receptor and oxytocin precursor throughout three developmental stages of A. femoralis tadpoles, before, during and after tadpole transport. Our results show an overall downregulation during tadpole transport, which indicates that during transport tadpoles enter a dormant state to slow down development until they are placed in water. Interestingly, the expression of oxytocin precursor did not vary between the three developmental stages. This might indicate that oxytocin is being recruited during transport, but does not lead to neurodevelopmental changes. In sum, here we present the first evidence of a dormant state during tadpole transport which might be an adaptive response to the terrestrial reproduction in poison frogs.

10
Early Vertebrates Were Not Slow: Rapid Life Histories in Devonian Agnathans

Okabe, N.; Pauly, D.

2026-04-29 paleontology 10.64898/2026.04.26.720944 medRxiv
Top 0.2%
1.1%
Show abstract

Life history strategies such as rapid growth and high population turnover rates observed in vertebrates have been thought to have emerged relatively late in evolution. However, very little direct evidence exists at the species level for early vertebrates. In this study, a large fossil collection of over 450 specimens of Protaspis spp, heterostracan agnathans from the Cottonwood Canyon Formation at Beartooth Butte, Wyoming, from the Early Devonian, was analyzed. Morphological observations, analysis of bone plate completeness, and length-frequency analyses using ELEFAN--commonly used in recent fish studies--were applied to reconstruct growth rates, cohort structure, and ontogenetic processes. Protaspis specimens exhibited a continuous growth series from juvenile to adult stages, and a clear cohort structure was identified from the length-frequency distributions. The ELEFAN analysis suggested a life-history characterized by rapid growth and a short life span, and these features remained consistent in subset analyses restricted by species or locality, confirming the robustness of the estimates. Furthermore, the integration of the dermal bone plates progressed during the late stages of ontogeny, revealing that the rapid growth during the juvenile stage preceded the completion of this defensive structure. Comparisons of their growth parameters with those of extant fishes show that Protaspis does not align with slow-growing, long-lived "living fossil" taxa, but instead clusters with small-bodied, fast-growing species. These findings suggest that life-history strategies involving rapid growth and high population turnover were already established in early jawless vertebrates, much earlier than previously assumed.

11
3-D Ontogenetic Staging Atlas of the Epaulette Shark Hemiscyllium ocellatum, a Laboratory Model for Shark Development

Dale, R. E.; Tulenko, F. J.; Hersey, L.; Currie, P. D.

2026-04-28 developmental biology 10.64898/2026.04.27.721166 medRxiv
Top 0.2%
1.1%
Show abstract

Chondrichthyans (cartilaginous fishes) form the sister group to osteichthyans (bony fishes) and therefore occupy a key phylogenetic position for comparative studies of early vertebrate evolution. Despite their importance, chondrichthyan development remains understudied relative to established model systems such as mouse, chick, and zebrafish, in part because of limited embryo accessibility and the lack of standardized laboratory resources for rearing. Here, we present the epaulette shark Hemiscyllium ocellatum, a small, oviparous shark as a tractable laboratory system for studying shark development. We provide an overview of epaulette shark husbandry requirements and generate a comprehensive micro-computed tomography imaging series spanning embryonic development through hatching. This dataset provides a three-dimensional anatomical atlas of development for a representative chondrichthyan species. By preserving whole embryos in three dimensions, micro-CT imaging enables developmental morphologies to be visualized at high resolution and in near-native anatomical context. Together with the recently published epaulette shark genome, this developmental atlas helps establish the Epaulette shark for comparative anatomical, developmental, and genomic studies.

12
First hematological and biochemical data in a rehabilitated giant pangolin (Smutsia gigantea) from southern Cameroon

Montblanc, M.; Harvey-Carroll, J.; Vanassche, J.; Donaldson, M.; Connelly, E.; Hywood, L.

2026-05-03 zoology 10.64898/2026.04.29.721582 medRxiv
Top 0.2%
1.0%
Show abstract

Giant pangolin (Smutsia gigantea) is one of the least studied pangolin species worldwide, with no published hematological and biochemical data available. We report the first blood parameters from a rehabilitated adult male from Campo Maan National Park (southern Cameroon). Hematological and biochemical findings are described and discussed in relation to available data from other pangolin species. These preliminary results provide the first reference framework for this species and highlight their relevance for clinical assessment, health monitoring, and conservation management.

13
Differential maturation in vestibular neuronal groups related to developmental motor reorganization in amphibians

Barrios, G.; Olechowski-Bessaguet, A.; Cardoit, L.; Fevrier, T.; Wattignier, A.; Tostivint, H.; Cattaert, D.; Thoby-Brisson, M.; Lambert, F. M.

2026-05-13 neuroscience 10.64898/2026.05.12.724497 medRxiv
Top 0.2%
1.0%
Show abstract

Vestibular neurons are core elements of the pathways involved in vestibulo-motor functions, such as vestibulo-spinal and vestibulo-ocular reflexes. To meet behavioral needs, electrophysiological neuronal properties are adequately adapted to the sensory-motor computation sustaining these distinct vestibular reflexes. During frog metamorphosis, there is a complete reorganization of the posturo-locomotor system while the oculomotor system remains minimally changed, probably associated to so far unknown changes in vestibular neuronal properties. We used this unique model to investigate the central developmental mechanisms underlying such a reconfiguration of vestibular-associated behaviors. Central vestibular neurons exhibit two types of electrophysiological phenotypes: tonic neurons with a continuous discharge and phasic neurons with a transitory discharge mainly due to the activation of Kv1.1 channel. Electrophysiological recordings and Kv1.1 immunolabeling of vestibulospinal (VS) and vestibulo-ocular (VO) neurons at both larval and juvenile stages revealed that the majority of VS neurons exhibited a tonic discharge in larvae but a phasic discharge in juvenile, while VO neurons remained mainly tonic throughout development. Changes in phasic and tonic neurons proportions in VS population are partly explained by neurogenesis. But we provide evidences that an electrophysiological phenotype switch is a concomitant developmental mechanism participating in the maturation of these central vestibular neurons. All together our results showed that the maturation process in central vestibular neuronal groups is highly related to the metamorphosis-induced remodeling of vestibulo-motor functions they are involved in, with the ultimate purpose of ensuring an adequate adaptation of neuronal elements properties to the developmental changes of behavioral constrains.

14
Gluconeogenesis and glycogen metabolism in the epidermis and endoderm of Xenopus tropicalis embryos and larvae.

Aoki, M.; Tsuchida, A.; Tamura, K.; Baba, O.; Yoshitake, K.; Furukawa, F.

2026-05-12 developmental biology 10.64898/2026.05.08.723674 medRxiv
Top 0.2%
1.0%
Show abstract

In many oviparous animals, egg yolk is the sole source of nutrition until feeding begins, and carbohydrates are present in only small amounts in the yolk. Glucose plays an important role in the developmental processes of various animals. In addition, gluconeogenesis has been reported to occur in the yolk syncytial layer (YSL) of cartilaginous fish and teleosts. In contrast, the role of gluconeogenesis in tetrapods remains unclear. In this study, we used Xenopus tropicalis, an anuran amphibian, which lacks YSL, and therefore provide an opportunity to examine the evolutionary conservation of gluconeogenic mechanisms among vertebrates. In X. tropicalis, liquid chromatography/mass spectrometry revealed that glucose levels increased before liver formation. Subsequent tracer experiments using 13C-labeled metabolic substrates detected gluconeogenesis activity from glycerol and lactate. Expression analyses showed that gluconeogenic genes are expressed in the epidermis and endoderm. Consistently, G0 knockout of fbp1, a key gluconeogenic gene, resulted in a significant reduction in glucose levels, affecting brain development. These findings first demonstrate that gluconeogenesis supports development of X. tropicalis. To the best of our knowledge, gluconeogenesis in developing epidermis has not been reported, highlighting previously unrecognized diversity in tissue-specific metabolism during vertebrate development. Comparative analyses across species will provide further insights into the evolution and functional significance of embryonic gluconeogenesis and nutrient metabolism.

15
Quantitative image analysis reveals no sexual dimorphism in the cellular dynamics of Drosophila heart tube formation

Perez--Vicente, R.; Balaghi, N.; Fernandez-Gonzalez, R.

2026-04-27 developmental biology 10.64898/2026.04.23.720323 medRxiv
Top 0.2%
0.9%
Show abstract

Congenital heart defects affect females and males differently. Several congenital heart defects arise during the formation of the heart tube, suggesting that heart tube morphogenesis may differ between females and males. We investigated if the fruit fly Drosophila melanogaster displays sexual dimorphisms in the cellular mechanisms of heart tube formation. Quantitative microscopy revealed no differences between females and males in the migration of cardiac progenitors to form the heart tube. Our results suggest that Drosophila do not display sexual dimorphisms in early cardiac development, and support the omission of sex as an experimental variable when investigating Drosophila heart tube morphogenesis.

16
Swung and spun in weightlessness : Evidence of immediate canalar underdetection of rotations in parabolic flight

Bonnard, T.; Doat, E.; Guehl, D.; Guillaud, E.

2026-07-06 neuroscience 10.64898/2026.06.30.735470 medRxiv
Top 0.2%
0.9%
Show abstract

Despite extensive research on vestibular function in microgravity, particularly during orbital and parabolic flight exposure, several gaps remain regarding the spontaneous behavior of vestibular organs under non-terrestrial gravitoinertial conditions. In particular, semicircular canal function, typically assessed through vestibulo-ocular reflex (VOR) recordings, has yielded inconsistent findings, with reports describing either no effect or reduced performance in microgravity. Moreover, many of these studies are limited by methodological constraints that reduce the interpretability of their conclusions. To clarify these discrepancies, we evaluated horizontal and vertical VOR responses during parabolic flights to assess semicircular canal function under transient weightlessness. Participants were passively rotated at a constant frequency and amplitude during normogravity and microgravity phases, centered along the head vertical or inter-aural axis. Eye movements were recorded binocularly using infrared eye-tracking in darkness to eliminate visual influences, while participants were tightly restrained to minimize proprioceptive variability. Results show a reduction in VOR gain during microgravity in both axes, despite consistent rotational stimulation across gravity conditions. In addition, VOR gain remained reduced after parabolas in the horizontal plane, whereas vertical VOR performance was preserved. These are the first results to demonstrate an immediate alteration of semicircular canal function in weightlessness. Possible sources of the reduction in VOR performance in 0g are discussed. We also propose that the observed post-flight effects reflect a down-weighting of semicircular canal inputs during multisensory integration.

17
Possible function of Hox2 in atrial siphon fusion of the ascidian Ciona

Liu, Y.; Yoshida, K.; Hozumi, A.; Itagaki, K.; Treen, N.; Sakuma, T.; Yamamoto, T.; Endo, T.; Sasakura, Y.

2026-07-14 developmental biology 10.64898/2026.07.13.738359 medRxiv
Top 0.2%
0.8%
Show abstract

The hallmark of sessile adult ascidians is a vase-like shape with a single oral and atrial siphon. Ciona, however, develops two atrial siphons after metamorphosis, which subsequently fuse into one. The mechanisms underlying this fusion are unknown. This study suggests that Hox2 controls this process. Hox2-knockout animals using Transcription-Activator-Like Effector Nuclease (TALEN) retain two atrial siphons throughout their lives. During normal fusion, epidermal cells between the siphons flatten along the anterior-posterior axis. This cellular flattening does not occur in Hox2-knockout animals, suggesting that the shape change in the epidermal cells produces tension, allowing the atrial siphon openings to converge at the midline for fusion. Hox2-knockout animals lack cupular organs, which are suspected hydrodynamic sensors in the internal epithelium of the fused atrial siphon and on the sperm duct. Among several knockout attempts, atrial siphon fusion was reproduced by only one TALEN pair, suggesting that this phenotype is driven by a mutation having a broader effect than those abolishing protein function. Many ascidians, unlike Ciona, develop a single atrial siphon shortly after metamorphosis. Our findings suggest that a phylogenetically conserved gene, Hox2, establishes this group-specific atrial siphon formation mechanism in Ciona.

18
Greater gray matter volume in somatosensory and parietal regions in elite skiers compared with other athletes

Nakagawa, K.; Kanosue, K.

2026-05-13 neuroscience 10.64898/2026.05.10.724084 medRxiv
Top 0.3%
0.6%
Show abstract

Elite athletes exhibit sport-specific neural adaptations, yet it remains unclear whether such changes reflect general effects of training or the unique demands of individual sports. Skiing requires postural control and whole-body coordination under dynamically unstable environments, placing high demands on somatosensory processing and sensorimotor integration. The present study aimed to identify structural brain characteristics specific to elite skiers by comparing them with athletes from other sports disciplines and non-athletes. T1-weighted MRI data were analyzed using voxel-based morphometry in 13 skiers, 23 non-ski control athletes and 25 non-athletes. Whole-brain analysis comparing skiers with non-ski athletes revealed a significant cluster showing greater gray matter volume in skiers compared with non-ski athletes in the left postcentral gyrus, extending into the superior parietal lobule. The identified cluster primarily encompassed cytoarchitectonic Areas 2 and 5L. These regions are involved in higher-order somatosensory processing and multisensory integration. Importantly, region-of-interest analysis demonstrated that gray matter volume within this cluster was greater in skiers compared with non-ski athletes and non-athletes, with no difference between non-ski athletes and non-athletes. These findings highlight the relative prominence of structural adaptations within somatosensory-parietal networks, reflecting the unique integration of proprioceptive and other sensory information required for elite skiing. Overall, these findings provide evidence for sport-specific structural brain differences in elite athletes and highlight the importance of somatosensory and parietal regions in sensorimotor integration relevant to skiing. These findings may have implications for understanding neural markers of expertise and may inform future approaches to training and performance evaluation in skiing.

19
A canine brain bank for comparative neuroscience and brain aging research

Darcy, S.; Beck, A.; Garrood, M.; Slaughter, A.; Parra, A.; Paredes, L.; Farrell, K.; Crary, J. F.; McKenzie, A. T.

2026-07-14 neuroscience 10.64898/2026.07.11.737944 medRxiv
Top 0.3%
0.5%
Show abstract

Companion animal brain banking has been recognized as a valuable approach for translational aging and dementia research. However, realizing the full value of canine brain banks depends on optimizing the methods that are used to collect and preserve the tissue. Whole brain perfusion fixation is one promising approach, but it is not yet well described in dogs. Here we describe the development of methods for a canine brain bank (currently n = 55), including whole brain perfusion fixation via aortic cannulation and brain extraction. We assessed perfusion quality using gross examination, post-perfusion CT, and histological clearance of blood vessels. We found that body weight and average flow rate per body weight were each significantly correlated with perfusion quality in our cohort. To illustrate the kind of analysis the bank could facilitate, we next performed a preliminary study of brain aging, one of our primary planned research applications. Using a pixel classifier applied to whole slide images, we quantified lipofuscin burden, and in this preliminary cohort found that it increased strongly with age in both the thalamus and hippocampus. In the hippocampus, lipofuscin burden was also elevated in dogs with owner-reported cognitive dysfunction, although the current cohort is too small to determine to what extent this association is independent of age. Preliminary electron microscopy studies also confirmed that perfusion fixed tissue from the bank is amenable to ultrastructural analysis. This work describes one approach for canine brain perfusion fixation and introduces a brain tissue resource that may help support future neuroscience research.

20
Diversity of Mammal Fauna in a Remnant of the Atlantic Forest in the Middle of a Megalopolis

Furtado, M.; Goncalves, A. F.; Fernandes, M. S.; Porfirio, G. E. O.; Camargo, M. M. d.

2026-06-08 zoology 10.64898/2026.06.05.730359 medRxiv
Top 0.3%
0.5%
Show abstract

A remnant Atlantic Forest fragment within Sao Paulos urban environment supports six mammal species, with Didelphis being most abundant, while maintaining natural temporal activity patterns and successful reproduction, demonstrating the conservation value of small protected areas within megacities for preserving native wildlife despite intense anthropic pressure. The Forest Reserve of the Institute of Biosciences (FRIB) is a remnant of the Atlantic Forest located at the University of Sao Paulo, city of Sao Paulo campus, in Brazil. Despite urban pressures such as altered food resources, pollution, pathogens, and interactions with invasive and domestic species, several wildlife species persist, demonstrating adaptability to urban environments. This study aimed to sample the mammal species diversity of FRIB using camera traps. A total of 367 records of six mammal species were obtained over 107 days of sampling, between June and November 2024, resulting in 7,872 hours of sampling effort. The species recorded were Callithrix jacchus, Callithrix penicillata, Didelphis aurita, Didelphis albiventris, and unidentified species of the orders Chiroptera and Rodentia. Didelphis sp. was the most recorded genera with 201 records. These results highlight the significance of this forest fragment in protecting wild animals in an environment facing intense anthropic pressure. ResumoA Reserva Florestal do Instituto de Biociencias (FRIB) e um remanescente da Mata Atlantica situado na Universidade de Sao Paulo, em Sao Paulo, Brasil. Apesar das pressoes urbanas, como mudancas nos recursos alimentares, poluicao, patogenos e interacoes com especies invasoras ou domesticas, diversas especies de animais selvagens continuam existindo, evidenciando sua capacidade de adaptacao aos ambientes urbanos. O objetivo deste estudo foi amostrar a diversidade de especies de mamiferos da FRIB atraves de armadilhas fotograficas. Durante um periodo de 107 dias de amostragem, de junho e novembro de 2024, foram obtidos 367 registros de seis especies diferentes de mamiferos, totalizando 7.872 horas de esforco. As especies registradas foram Callithrix jacchus, Callithrix penicillata, Didelphis aurita, Didelphis albiventris, alem de especies nao identificadas das ordens Chiroptera e Rodentia. Didelphis sp. foi o genero com maior numero de registros (n=201). Esses resultados ressaltam a importancia desse fragmento florestal na protecao da fauna selvagem em um ambiente que enfrenta intensa pressao antropica.