The Anatomical Record

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.

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.

Tessellated calcified cartilage (TCC) is a hallmark of the chondrichthyan skeleton, yet its development early in ontogeny across the four major groups (batoids, galeomorphs, squalomorphs, and holocephalans) remains poorly understood. Specialised traits of TCC, such as multi-layered TCC and internal mineralised trabeculae, typically develop in response to feeding mechanics. In this study, we evaluated TCC morphology in the jaws of 12 representative taxa to observe its structure at an early ontogenetic stage to determine whether these specialised features had yet developed. Batoids consistently exhibited well-developed, homogeneous, polygonal tesserae early in ontogeny regardless of jaw morphology or feeding habit. In contrast, galeomorphs displayed high morphological heterogeneity. Notably, we document the first report of an extensive internal trabecular network in a non-batoid elasmobranch, observed in Ginglymostoma cirratum, which may serve to resist the mechanical pressures of specialised suction feeding. Furthermore, we identified voussoir tesserae in galeomorphs for the first time, extending their documented presence across all elasmobranch groups, where they display an inverted aspect ratio (wider than tall) compared to mature forms. The durophagous Mustelus mustelus exhibited surprisingly poor TCC development despite being a durophagous feeder, pointing to a pronounced ontogenetic lag. In Squatina oculata, TCC was characterised by large and thick tesserae and extensive fused tesseral regions which may relate to its explosive ambush predation mode, whereas the holocephalan Chimaera exhibited a poorly mineralized, mesh-like structure without resolvable discrete tesserae or trabeculae-matching findings from previous studies. Across all specimens, multi-layered TCC was absent, confirming that multi-layering develops later in ontogeny. These results demonstrate that generalised models of TCC development based on one group or a few taxa fail to capture the broader diversity of TCC morphology. It also opens up many exciting avenues for further study, and forms the basis for comparisons with fossil chondrichthyans, to investigate the evolution of TCC.

The human brainstem is a complex division of the brain comprised of more than 200 nuclei and fiber tracts. The brainstem is essential for the functioning of the entire body. We introduce here the most detailed human brainstem Atlas across the human lifespan: fetus, child, adult. ANCHOR, the Atlas of Neurochemical Characterization of the Human Brainstem, is an online platform that includes more than 800 serial histological sections, stained for Nissl and seven immunochemical (IHC) markers, from the human brainstem of three ages: 25 fetal gestational weeks (GW), 9 years old, and 54 years old. This makes ANCHOR the most comprehensive human brainstem Atlas to date. In these three brainstems, we identified and manually annotated over 200 structures. We further characterized these structures with the seven IHC markers. We specifically describe the catecholaminergic groups in the human brainstem across all three age groups. In addition, we identified the protoplasmic commissural dendrites of the hypoglossal nucleus and we describe the pretectal nuclei in the Nissl-stained fetal 25 GW brainstem. ANCHOR includes an online viewer that integrates multimodal data, from magnetic resonance imaging and block face imaging to Nissl- and IHC-stained serial sections and 3D reconstruction of the entire brainstem. For the 9-year-old specimen, the online viewer allows simultaneous navigation of annotated sections with corresponding IHC, for viewing the specific region-wise cellular features accessible at https://anchor.humanbrain.in/.

Microcomputed tomography (micro-CT) is a useful tool that can be utilised for 3D structural characterisation and volumetric quantification of small biological specimens. Its potential application is particularly valuable within the field of cardiac development, where phenotypic profiling at the whole organ, cell, and molecular level is often most informative within the same sample. Consequently, this study sought to develop a multimodal imaging protocol to enable 3D phenotypic characterisation of embryonic avian hearts (iodine-based contrast X-ray imaging) prior to immunohistochemistry-based cell and molecular analysis. Micro-CT parameters were tested to establish an optimal protocol for 3D analysis of embryonic cardiac specimens across multiple developmental timepoints. Optimised parameters provided reliable and reproducible 3D analysis of cardiac macrostructures. Sodium thiosulphate treatment of X-ray imaged hearts effectively reversed the iodine-based contrast stain whilst maintaining antigen availability of nuclear, membranous, and cytoplasmic targets in traditional downstream imaging studies. Together, this study demonstrates a robust and highly efficient multimodal imaging strategy to comprehensively characterise cardiac morphology in avian embryos and may serve as a versatile foundation for a broad range of bioimaging applications within the wider scientific community.

Hydrozoa is a group of relatively simple animals with a well-developed nervous system. The nervous system in all hydrozoan medusae is highly conserved and includes outer and inner nerve rings at the bell margin, a neural network in the manubrium, and radial neural pathways that connect them. However, one element of the nervous system shows substantial variability among species: the subumbrella neural network. We examined the structure of the nervous and muscular systems in the subumbrella of 14 species of hydrozoan medusae. The main conclusion of this study is that the distribution of neural networks in the subumbrella strongly correlates with the distribution of smooth radial muscles. This correlation suggests that smooth radial muscles are the primary target of the subumbrella nervous system. Most species in the order Anthoathecata show a trend toward secondary loss of the neural networks and radial smooth muscle fibers in the subumbrella region, concentrating neural elements and smooth muscles only in the radial pathways along the radial canals. By contrast, all studied species in the order Leptothecata have neural networks in the subumbrella area, as well as radial smooth muscle fibers spread throughout the entire subumbrella region. The correlation between radial smooth muscles and the nervous system is also observed in the radial pathways along the radial canals. All species with thick bundles of smooth radial muscles along the radial canals have clearly defined, dense neural pathways running along or even embedded within the smooth muscle bundles.

Traumatic brain injury (TBI) is a characteristic feature of neurodegenerative diseases such as Alzheimers disease and chronic traumatic encephalopathy. Small animal models have been used to establish clinically relevant biomarkers of neuropathology, however, they show significant anatomical differences from humans and are affected by artificial experimental manipulations, making them often unsuitable for longitudinal study of repetitive mild TBI. Building on a previous study of neuropathology in headbutting bovids in the wild, this pilot study investigated whether freely headbutting domestic goats, which naturally engage in low-intensity, high-frequency head impacts, accumulate measurable biomarkers of neurodegeneration in cerebrospinal fluid (CSF) and brain tissue. Over a six-month period, three male goats (Capra hircus) were allowed to freely headbutt under continuous video surveillance. Monthly CSF samples were collected, and concentrations of key neurodegeneration biomarkers were measured via multiplex immunoassays, including amyloid {beta} ; peptides (A {beta} 40, A {beta} 42), total and phosphorylated tau (tTau and pTau), glial fibrillary acidic protein (GFAP), S100 calcium-binding protein B (S100B), and neurofilament M (NF-M). Postmortem immunohistochemistry was conducted on prefrontal cortical tissues using antibodies targeting pTau, GFAP, and S100B. Head impact kinematics were quantified using horn-mounted accelerometer and inclinometer sensors that recorded linear acceleration, rotational velocity, and head orientation during naturally occurring headbutting events. Several notable trends were observed. Phosphorylated tau as well as reactive astrocytes were detected in the brain tissue, mirrored by elevated GFAP detected in the CSF. PET TSPO was unsuccessful, however, FDG PET revealed frontal-dominant activity in all goats, and one with asymmetrical activation. Overall, the goats sustained 5,000-7,000 head impacts each over six months, with forces up to 388 N and peak acceleration up to 16.5 g. This multi-modal observational study is the first to characterize neurodegeneration biomarkers and kinematics in headbutting goats. Even at one year old, the combination of pTau and gliosis in both the brain tissue and CSF indicates that the goat s repetitive head impacts begin to show neurodegenerative consequences early in life. Likely, the severity of these consequences increases with headbutts and age, eventually resulting in chronic neurodegeneration. This system shows promise as a large-animal model for the longitudinal study of the onset and progression of neurodegenerative disease.

The feline auditory cortex is understood to consist of 13 distinct subregions with unique anatomical and functional properties. Differential patterns of SMI-32 immunoreactivity are commonly used to identify the borders between these subregions; however, the detailed description of areal differences that is commonly cited did not include descriptions of the patterns observed along the posterior ectosylvian gyrus. Thus, the current manuscript aims to provide a more complete data set that can used to delineate the dorsal, intermediate, and ventral divisions of the posterior ectosylvian gyrus (auditory cortical regions dPE, iPE, and vPE, respectively) based on SMI-32 reactivity using the same methods and measures. Taken together, the current data and those published previously allow for a standardized approach to identifying all 13 auditory cortical subregions in this essential model of auditory cortical structure and function.

Extraocular motoneurons are the final neuronal relay implicated in gaze motor control and are known to be subdivided in functional subgroups, differently implicated in ocular motion dynamics. However, the maturation of these functional populations of extraocular motoneurons, in relation with the development of gaze-stabilizing reflexes remains largely unexplored. In amphibian tadpoles, the angular vestibulo-ocular reflex (VOR) appears later than other visuo-vestibular ocular reflexes and matures until the metamorphosis climax. Two types of Abducens motoneurons have been described to participate to the angular VOR in larval frog: spontaneous motor units, exhibiting a robust resting activity and silent motor units recruited only during head motion. The aim of this study was to investigate the maturation of these two types of Abducens motor units in relation with the development of the angular VOR by evaluating their discharge dynamic in response to head rotation in semi-intact preparations of larval Xenopus laevis. During larval life, the discharge modulation during sinusoidal head rotations increases significantly for silent units only, demonstrating a better sensitivity of this Abducens motoneuron sub-population to horizontal semicircular canal activation. In addition, this functional maturation was accompanied by an increase of the myelination in the lateral rectus motor nerve, promoting a faster conductivity in late larval stages than in early one. These findings showed that the development of the angular VOR is supported by a selective maturation of extraocular motoneurons subpopulations, specifically implicated in the improvement of the ocular kinematic during the reflex.

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.

Despite major advances in the study of cerebellar neurogenesis, cerebellar angiogenesis during embryogenesis remains poorly described. Recent advances in tissue clearing, light-sheet microscopy, and artificial intelligence have increasingly enabled detailed 3D modelling of cerebellar vasculature at early developmental stages. Here, vascular networks in mouse embryos from E11 to birth (P0) were labelled with podocalyxin, SMA, and PECAM-1 antibodies together with the nuclear marker TO-PRO-3 iodide, cleared, imaged by light-sheet microscopy, and finally modelled and quantitatively analyzed using Imaris and VesselVio. Our mapping reveals that the three main paired cerebellar arteries--the superior (SCA), anterior inferior (AICA), and posterior inferior (PICA) cerebellar arteries--emerge sequentially between E11 and E13 and display significant topographical variability comparable to that observed in humans. Morphometric analysis demonstrates distinct developmental dynamics, with SCA growth proportional to cerebellar expansion, whereas the AICA and PICA exhibit accelerated extension during later embryonic stages. Interestingly, the PICA does not reach the cerebellum before birth, highlighting the question of its contribution to embryonic cerebellar vascularization. The intrinsic vascular network evolves from a rudimentary bilayer at E11 into a highly branched architecture organized around radial penetrating vessels, giving rise to collaterals that progressively colonized the cerebellar parenchyma during foliation and lobulation. These vascular changes temporally coincided with the successive stages of cerebellar neurogenesis, supporting an interplay between vascular and neuronal development. Together, our findings provide the first spatio-temporal three-dimensional atlas of cerebellar vascularization during mouse embryogenesis, establishing a reference framework for investigating cerebellar angiogenesis in developmental and pathological conditions. HighlightsO_LIThis work is the first 3D modelling of the cerebellar vasculature in mouse embryo. C_LIO_LISCA, AICA, PICA develop through distinct spatial and temporal growth programs. C_LIO_LIPICA does not contribute to cerebellar vascularization before birth. C_LIO_LIThe intra-cerebellar vascularization evolves at E11 from a simple vessel bilayer. C_LIO_LIBetween E13 and P0, radial vessels form collaterals colonizing cerebellum. C_LIO_LIThe vascular changes temporally coincided with cerebellar neurogenesis. C_LI

Background: Brain banks usually provide small tissue blocks fixed by immersion in neutral-buffered formalin (NBF). While still underexploited for research, gross anatomy laboratories could provide full brains fixed by perfusion with solutions better suited for gross anatomy dissection. However, the chemicals in these solutions might have a different impact on histology protocols for cell quantification than in NBF-fixed brains. The main goal of this study is to compare the effects on the number and size of labeled neurons of the primary motor cortex (PMC) of mouse brains fixed with three different solutions: (1) NBF, typical of brain banks, (2) a saturated salt solution (SSS), and (3) an alcohol-formaldehyde solution (AFS), both used in human anatomy laboratories. Methods: 27 C57BL/6J mouse brains were perfused with the NBF (N=9), SSS (N=9) or AFS (N=9), then cut in 40-m slices and processed with immunohistochemistry to target neurons. Various quantitative variables were assessed manually and automatically on photomicrographs of 3 regions of interest (ROIs) of the PMC per specimen, namely the total and individual neuronal profile areas, number and diameters. The effects of the three fixatives on these variables were compared using ANOVA or Kruskal-Wallis, depending on the distribution. For measures on individual cells, a generalized linear mixed model was applied. Dice coefficients and correlations were applied to evaluate the agreement of the manual and automatic methods. Results: There was no significant difference between the brains fixed by the three fixatives for the total and individual cell areas, the total cell count and the cell diameters. The values obtained from manual and automatic measures had an overall good agreement (Dice coefficients > 0.79). Conclusion: It was found that the SSS and AFS had similar impacts on the quantitative variables in the tissue as the NBF. These results are promising for neuroscientists interested in using brains from anatomy laboratories for quantitative research on neurons from the PMC.

Humans are widely regarded as unusually slow to develop, exhibiting prolonged childhood and extended dependence on caregivers. However, this view is based primarily on comparisons with other primates, leaving unresolved whether humans remain distinctive within the broader diversity of mammals. We addressed this question by situating human development in a comparative framework using gestation length, weaning age, and age at sexual maturity for both sexes across 462 mammalian species representing 25 orders. Each trait was examined both as an absolute value and as a proportion of the longest verified captive lifespan. In absolute terms, human developmental traits fell within the upper range of mammalian variation. When expressed relative to lifespan, however, gestation shifted toward the lower end of the distribution, whereas weaning age and sexual maturity occupied intermediate positions, indicating that human developmental timing largely follows general mammalian scaling patterns rather than representing a pronounced outlier. These findings suggest that key features of human dependency are better understood as extensions of broader evolutionary trends than as uniquely human life-history characteristics.

The human bony labyrinth has attracted increasing interest because of its taxonomic, evolutionary, and functional significance. Although sexual dimorphism has been reported in several aspects of the temporal bone, the extent to which sex, age, size, and allometry contribute to labyrinth shape variation remains poorly understood. Here, we investigated patterns of sexual shape variation in the human bony labyrinth using three-dimensional geometric morphometrics in a sample of 98 archaeological individuals from South America with known genomic sex. Centroid size and allometric effects were assessed in a subset of 90 individuals with comparable metric scaling. In addition to analysing the complete labyrinth, the cochlea and semicircular canals were examined separately to evaluate region-specific patterns of sexual shape variation. Principal Component Analysis showed extensive overlap between females and males, and overall labyrinth shape did not differ significantly between sexes. Males exhibited significantly larger labyrinths than females, and centroid size explained a small but significant proportion of overall shape variation. Regional analyses showed no evidence of significant sexual shape differences in the cochlea or in any individual semicircular canal when analysed separately. In contrast, the combined semicircular canal system exhibited subtle but significant sexual shape variation independent of centroid size, whereas morphological disparity did not differ between sexes. The geometric comparison of the female and male consensus configurations further showed that sexual shape variation was regionally heterogeneous. Whereas the cochlea exhibited a pattern of localized changes with low directional coherence, the semicircular canals displayed more coordinated regional shape changes. The male consensus also exhibited slightly higher canal circularity across all three semicircular canals, particularly the posterior canal, while differences in canal-plane orientation remained minimal. These findings demonstrate that sexual shape variation in the human bony labyrinth is subtle and anatomically partitioned among its components. Although significant sex differences in centroid size were detected across most anatomical regions, overall labyrinth shape and cochlear morphology were primarily influenced by allometry, whereas significant sex-related shape differences were detected only when the semicircular canals were considered as an integrated anatomical system. These findings demonstrate that sexual dimorphism in the human bony labyrinth is subtle but regionally heterogeneous, with the cochlea and semicircular canals exhibiting distinct patterns of shape variation, suggesting that these structures are influenced by different developmental, functional, and evolutionary processes.

Stereotaxic brain surgery is a foundational neurosurgical technique used to deliver chemical, pharmacological, or genetic material to specific brain regions, or to precisely implant electrodes and stimulators. Accurate targeting depends on reliable identification of skull landmarks, particularly bregma and lambda. Here we present a photogrammetry-based automated small animal stereotaxic platform that uses a single, freely handheld camera, such as a standard smartphone, to generate high-resolution, polychromatic 3D skull reconstructions. Because photogrammetry requires no fixed overhead hardware, the surgical field remains fully accessible for instruments, microscopes, and other equipment. The resulting color reconstructions substantially improve identification of bregma and lambda compared to monochromatic approaches, and the higher spatial resolution translates directly into improved targeting accuracy and surgical speed. The system operates by a user moving a handheld camera around the exposed skull. The platform automatically produces a detailed 3D mesh and computes stereotaxic coordinates without manual measurement. Together, these properties yield a practical, accessible yet accurate platform for automated small animal neurosurgery. We previously described a structured illumination approach in combination with a Steward platform; however, that system required a fixed projector and camera array that occupied critical surgical workspace and produced monochromatic meshes that complicated landmark identification. The photogrammetry-based method described here overcomes both limitations while retaining full compatibility with the Steward platform as a stereotaxic base.

Prolonged low-temperature exposure may extend the preservation window of mammalian cells but can also disrupt cellular homeostasis and ultimately compromise cell viability. This study investigated the time-dependent phenotypic and transcriptomic responses of primary canine dermal fibroblasts to sustained hypothermic stress. Passage-three fibroblasts were continuously maintained at 15 for up to 15 days, with samples collected on Days 0, 3, 6, 9, 12, and 15. Cellular morphology, metabolic activity and viability, and apoptosis were evaluated using bright-field microscopy, Cell Counting Kit-8 assays, and Annexin V-FITC/propidium iodide flow cytometry, respectively. RNA sequencing was performed to characterize dynamic transcriptional changes throughout the exposure period. Early low-temperature exposure was associated with relatively preserved cellular morphology and viability, suggesting a transient adaptive response. With increasing exposure duration, fibroblasts exhibited progressive morphological deterioration, reduced metabolic activity, loss of adhesion, and increased apoptosis. Time-series transcriptomic analysis further revealed temporally coordinated and stage-dependent gene-expression programs associated with metabolic regulation, cellular stress responses, structural homeostasis, and cell survival. Integration of phenotypic and transcriptomic data demonstrated that the response of primary canine dermal fibroblasts to 15 was dynamic rather than linear, progressing from early adaptation to cumulative dysfunction during prolonged exposure. These findings provide a framework for defining the low-temperature tolerance of primary canine dermal fibroblasts and may inform the optimization of protocols for their short- to medium-term preservation and transportation.

Perfusion fixation is widely used in neuroscience to prepare mammalian brain tissue for histological and ultrastructural analysis. Perfusion protocols are commonly assessed using macroscopic indicators such as gross appearance and neuroimaging, which assess the extent to which perfusate has been distributed throughout the brain. There is a critical need to determine to what extent these metrics can accurately predict high-quality ultrastructural preservation, particularly as new perfusion protocols are developed for connectomics. In this technical report, we describe evidence that these two measures can be decoupled by the addition of dehydrating agents to the perfusate solution. In three human brain donors and one canine brain donor perfused with a fixative solution containing 10% mannitol and 10% polyethylene glycol 35 kDa, macroscopic and radiological indicators of perfusion quality appeared adequate or favorable. However, electron microscopy revealed expanded extracellular space, shrunken cellular processes, and distorted cell membranes, consistent with an osmotic shock artifact resulting from severe hyperosmotic dehydration. Similar ultrastructural artifacts were observed in a canine brain donor perfused with 20% mannitol in 20% neutral buffered formalin without PEG. We compare these ultrastructural findings with findings from previously reported cases perfused with standard neutral buffered formalin without osmotic additives. These findings illustrate a risk of optimizing brain perfusion protocols designed to preserve neural circuitry based on macroscopic or radiological perfusion quality metrics alone, since these metrics can be satisfied while the ultrastructure is severely compromised.

Abstract Introduction: Despite advances in pain management, effective analgesics in pain situations remain elusive. Opioids and non-opioids carry risks of neurotoxic and psychedelic effects with adverse physiological outcomes. Indian instrumental music (IIM) mitigates subacute pain by rewiring neurochemical synergy as an evidence-based, non-invasive, non-pharmacological system to mitigate pain. Objective: Investigating therapeutic efficacy of IIM in mitigating subacute pain by analyzing behavioral, peripheral, and central neurochemical re-tuning. Methods: Mice were divided into Control, Pain, Pain+Music, and Music groups. Pre-treatment behavioral parameters were compared with those observed after 14 days IIM exposure. Evaluations included nociceptive latencies (hot-plate/tail-flick), locomotion (Open Field Test), and anxiety (Elevated Plus Maze). Molecular analyses quantified peripheral neuropeptides (SP, NK-1R, CGRP), serum cortisol, spinal neurotrophic factor, neurotransmitters (glutamate, GABA, dopamine (DA), 5-HT), BDNF, and mRNA expression of BDNF, Ntrk1R/2R, and D1R in cortex, thalamus, hippocampus and hypothalamus. All procedures adhered to IAEC guidelines. Results: IIM yielded 3.9-4.4-fold antinociceptive improvements, 3.3-fold locomotor restoration, and 3.6-4.9-fold anxiolysis. 14 days IIM exposure reduced peripheral nociceptive-neuropeptides 1.3-2.0-fold (SP, NK-1R, CGRP), serum cortisol 1.3-fold, and spinal glutamate, serotonin levels 1.5- and 1.3-fold. An enhanced expression of spinal GABA, DA about 1.5-fold, and BDNF by 1.3-fold was observed after music listening. Brain-region-specific differential mRNA-expression at cortex, thalamus, hypothalamus and hippocampus revealed the neuromodulatory impact of rhythmic music in a formalin-induced murine pain-model. Conclusion: Gross reduction of pain parameters demonstrates therapeutic potential of IIM as multilevel neuromodulator to suppress the multidimensional stressor, pain, via peripheral desensitization, spinal E-I balance, and differential calibration of BDNF/Trk/D1R plasticity at specific brain-regions. Keywords: Pain, Non-Pharmacological Method, Indian Instrumental Music (IIM), Behavior, Neurotransmitters, Neuroplasticity, mRNA Expression.

Tree shrews (Tupaia belangeri) are increasingly used in comparative neuroscience, yet their respiratory physiology remains poorly characterized. We quantified spontaneous breathing and respiratory rhythm variability in awake adult tree shrews (n = 10; 5 males, 5 females) using whole-body plethysmography. Respiratory frequency decreased by approximately 16% with acclimatization to the recording chamber, while respiratory timing, body-mass-normalized respiratory amplitude, inspiratory flow, and minute ventilation remained relatively stable. After acclimatization, mean respiratory parameters were similar between sexes, but short-term breath-to-breath variability (SD1) was greater in males than females, whereas SD2 was comparable. These findings establish baseline respiratory characteristics in awake tree shrews and identify sex-dependent differences in short-term respiratory rhythm stability.

Adult sex ratios in mammals are usually female-biased, but the northern mole vole (Ellobius talpinus) (Pallas, 1770), a cooperatively breeding subterranean rodent, shows a persistent male bias that increases with age. Combining four years of capture-mark-recapture data with radiographic age estimation and genetic parentage data, we modeled apparent survival and state transitions (young-of-the-year, breeder, non-breeder) separately by sex. Young individuals showed significantly lower apparent survival than adults in both sexes, consistent with dispersal occurring predominantly in the first year of life. Within each age class, females showed consistently lower apparent survival than males, and this pattern held within breeding and non-breeding status groups alike, with female breeders showing lower apparent survival than male breeders. These results point to female-biased natal dispersal, an atypical pattern for mammals. We propose that faster turnover of reproductive females than males, in combination with singular breeding, favor female dispersal in search of vacant breeding positions, while promoting male philopatry and facultative polyandry.