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ORIGINAL ARTICLES

Open Access

What is new in flexor tendon pulleys and the gaps between them in triphalangeal fingers of the hand?

  • Version of Record online: 28 February 2024
Description unavailable

A: Third left finger showing all pulleys of the digital sheath present (8). B: Fifth right finger showing a pattern conformed only by annular pulleys (A1-A2-A3-A4) (methylene blue has been used to facilitate identification of the pulleys) (d: distal, u: ulnar, r: radial).

Open Access

Neurovascular anatomy of the developing human fetal penis and clitoris

  • Version of Record online: 28 February 2024
Description unavailable

We have demonstrated the vascular and neuronal distribution of the human fetal clitoris and penis from 8 to 12 weeks of fetal age. At 8 weeks, we observed identical neurovascular distribution. At 10 weeks, fusion of the urethral folds is noted in the proximal shaft of the penis, and co-expression of both neuronal and vascular markers is noted specifically at the fusion point. At 11 weeks, the clitoral ridge, which is a well-vascularized structure is identified in the clitoral shaft.

Morphological examination of abdominal vertebral bodies from grass carp using high-resolution micro-CT scans

  • Version of Record online: 28 February 2024
Description unavailable

The grass carp vertebral centrum demonstrates bilateral symmetry (left/right), yet the centrum focus is shifted dorsally and cranially, breaking dorsoventral and craniocaudal symmetry. As the vertebral parapophyses and spinous processes are slanted caudally, the direction of muscle action during swimming may create a gradient of stresses from cranial to caudal, resulting in a more robust caudal aspect of the vertebral centrum.

Open Access

Effect of deletion of the protein kinase PRKD1 on development of the mouse embryonic heart

  • Version of Record online: 28 February 2024
Description unavailable

Congenital heart disease accounts for a third of all congenital defects. The role of protein kinase D1 in cardiogenesis and CHD was studied using a transgenic mouse model (Prkd1em1) carrying deletion of exon 2 (em1), causing loss of function. Morphological 3D analysis by high-resolution episcopic microscopy has shown a range of CHDs occur in the Prkd1em1 embryonic day E15.5 and the postnatal day (P) 6/7 hearts. Ao, aorta; AS; atrial septum; LA, left atrium; LV, left ventricle; PT, pulmonary trunk; RA, right atrium; RV, right ventricle; VS, ventricular septum.

Open Access

Brain volume in infants with metopic synostosis: Less white matter volume with an accelerated growth pattern in early life

  • Version of Record online: 28 February 2024
Description unavailable

To gain insight into the pathophysiology of metopic synostosis and its association with neurodevelopmental disorders, we studied preoperative brain volumes of non-syndromic metopic synostosis patients compared to controls using MRI. We found smaller total white matter volume with accelerated white matter growth in metopic synostosis patients, similar to white matter growth patterns in autism. Our findings suggest a generalized intrinsic brain anomaly in the pathophysiology of metopic synostosis.

Open Access

Anatomical design and production of a novel three-dimensional co-culture system replicating the human flexor digitorum profundus enthesis

  • Version of Record online: 23 February 2024
Description unavailable

Anatomical morphometrics have been used to design and manufacture models of the flexor digitorum profundus tendon to bone insertion in vitro. This innovative approach can be used to design models of other enthesis regions with anatomical and clinical applicability.

Open Access

Trabecular architecture of the distal femur in extant hominids

  • Version of Record online: 21 February 2024
Description unavailable

This study provided a holistic approach of trabecular bone architecture within the hominid distal femur. Trabecular structure in Homo reflects habitual use of extended knee postures during bipedalism, habitual use of flexed knee posture during terrestrial and arboreal locomotion in African apes, and the highly mobile knee joint in Pongo. This study offers a comparative sample of trabecular structure in the hominoid distal femur and can contribute to future studies of locomotion in extinct taxa.

Open Access

The vomeronasal system of the wolf (Canis lupus signatus): The singularities of a wild canid

  • Version of Record online: 16 February 2024
Description unavailable

The vomeronasal system (VNS) of the Iberian wolf is fully functional for pheromone-mediated communication. Microscopic differences between the VNS of wolves and domestic dogs suggest neural changes due to domestication. These findings provide insights for innovative semiochemical-based wolf population management strategies.

Open Access

Fatty infiltration of gastrocnemius–soleus muscle complex: Considerations for myosteatosis rehabilitation

  • Version of Record online: 16 February 2024
Description unavailable

Fatty infiltration of the gastrocnemius–soleus complex is common in the elderly and displays a medial to lateral progression. As the calf contour is preserved, the condition is not visible externally.

Entheseal variation and locomotor behavior during growth

  • Version of Record online: 15 February 2024
Description unavailable

Entheseal changes of juveniles have not yet been studied with a systematic approach. This contribution aims at investigating the morphological changes occurring at two lower limb fibrous entheses to highlight a potential link between their morphological features and skeletal maturity in relation to sex, age, and locomotor developmental patterns.

Open Access

Springhares, flying and flightless scaly-tailed squirrels (Anomaluromorpha, Rodentia) are the squirrely mouse: comparative anatomy of the masticatory musculature and its implications on the evolution of hystricomorphy in rodents

  • Version of Record online: 06 February 2024
Description unavailable

The digital dissection of the masticatory musculature of (a) Anomalurus, (b) Idiurus, (c) Zenkerella, and (d) Pedetes reveals a great degree of diversity in morphology. These taxa present a hystricomorphous condition of the skull that largely differs from those of other rodents with an enlarged foramen and reaffirms the significance of the descriptive anatomical features of the masticatory apparatus as a valuable source of information for understanding the evolutionary relationships among closely related taxa.

METHOD

Open Access

How to make a digital reconstruction of the human ribcage

  • Version of Record online: 05 February 2024
Description unavailable

This manuscript aims to present an accessible protocol for digitally reconstructing the human ribcage from commingled costo-vertebral remains.

ORIGINAL ARTICLES

Deploy the proboscis!: Functional morphology and kinematics of a novel form of extreme jaw protrusion in the hingemouth, Phractolaemus ansorgii (Gonorynchiformes)

  • Version of Record online: 03 February 2024
Description unavailable

We describe a novel form of jaw protrusion in Phractolaemus ansorgii, a fish that feeds with a deployable proboscis-like snout that can be protruded to a distance greater than 30% of its head length. This proboscis is unique from the feeding apparatuses of other fishes; it features a dentary that is rotated nearly 180 degrees in the head and an oral aperture that is supported by flexible hyaline cartilages rather than bone, which may be advantageous for feeding along irregular benthic substrate.

Open Access

Evaluating the muscle attachment hypothesis for sagittal cresting in Gorilla and Pongo

  • Version of Record online: 03 February 2024
Description unavailable

To evaluate the ‘muscle attachment hypothesis’ and the ‘sexual selection hypothesis’ for sagittal cresting in Gorilla and Pongo, this study investigates sex-specific associations between regions of the mandibular ramus and neurocranium associated with mastication in a dentally mature sample of Gorilla and Pongo. Our results show that patterns of sagittal crest, temporalis muscle attachment area, mandibular ramus and coronoid process variation observed in male gorillas and orangutans cannot be explained by the muscle attachment hypothesis alone.

Effects of long-term voluntary wheel running and selective breeding for wheel running on femoral nutrient canals

  • Version of Record online: 02 February 2024
Description unavailable

We investigated femoral nutrient canal phenotypic plasticity in response to physical activity in mice from four replicate high runner (HR) lines bred for voluntary wheel running, along with four non-selected control (C) lines. Shown are 3D models of femoral nutrient canals, re-oriented to measure transverse slices for cross-sectional area. Many nutrient canal shapes were encountered. Voluntary wheel running for 12 weeks increased the number of canals in C mice but decreased it in HR mice.

Postnatal changes in thyroid cartilage shape and cartilage matrix composition are not synchronized in Mus musculus

  • Version of Record online: 01 February 2024
Description unavailable

We studied the matrix composition of laryngeal cartilage and its relationship with cartilage shape in a mouse model. The changes in cartilage shape were not synchronized with changes in cartilage matrix composition, and the mineralization pattern was homogenous.

Open Access

Maxillary morphology of chimpanzees: Captive versus wild environments

  • Version of Record online: 31 January 2024
Description unavailable

Captive and wild chimpanzees were compared using three-dimensional geometric morphometric methods to assess whether their maxillae are morphologically different. Overall, this study confirms that captive individuals are atypical specimens, unrepresentative of the wild morphology, and that they should not be included in craniometric analyses when the objective is to characterise the species.

Early spiral arteriole remodeling in the uterine–placental interface: A rat model

  • Version of Record online: 30 January 2024
Description unavailable

Here we characterize the rat as a model system for mammals with hemochorial placentation, teasing apart the understudied earliest events in the remodeling of parental uterine spiral arterioles. We show that the rat uterine-placental interface increases in size and vascularity rapidly, before trophoblast invasion. The uterine arterioles in rat follow a sequence of anatomical changes similar to those in humans, making the rat a tractable model in which to better understand the cell/cell interactions occurring in this tissue microenvironment over time.

Open Access

The changing morphology of the ventricular walls of mouse and human with increasing gestation

  • Version of Record online: 29 January 2024
Description unavailable

Jensen et al report a combined morphometrical and pictorial analysis of the development of the cardiac ventricular walls of mouse and human. Pronounced morphological changes are documented. That the trabecular and compact layer grow at different rates with respect to each other is the major driver of morphological change. No evidence was found to support the process of compaction in driving morphological change. Factors that affect the assessment of morphological changes of the ventricular walls, and these tend to create a bias towards finding compaction, are discussed.

Open Access

Variation in the sacrum of phytosaurs: New evidence from a partial skeleton of Machaeroprosopus mccauleyi

  • Version of Record online: 29 January 2024
Description unavailable

Phytosaurs, a group of Triassic semi-aquatic archosauriform reptiles, are thought to vary in their numbers of sacral vertebrae from two, the plesiomorphic condition for archosauriforms, to three, with the addition of a sacralized dorsal (i.e., dorsosacral) vertebra. In this study, we demonstrate the presence of a sacralized first caudal (i.e., caudosacral) vertebra in a sacrum belonging to Machaeroprosopus mccauleyi. Additionally, we show that a dorsosacral vertebra is common in phytosaur specimens from the Chinle Formation and Dockum Group of the southwestern United States and suggest that it may be widespread among phytosaurs. The addition of sacral vertebrae potentially aided adaptation to larger body sizes or more terrestrial lifestyles in certain taxa.

Is human height based on a Lucas sequence relationship between the foot height, tibial length, femur length and upper body length?

  • Version of Record online: 29 January 2024
Description unavailable

We conclude that height is made up of a series of body segments in an ascending Lucas sequence. If foot height is given a value of 1 unit, then tibial length is 4 units, femur length is 5 units, upper body length is 9 units, and total height is 19 units.

Temporal involvement of phosphatidylinositol 4-phosphate 5-kinase γ in differentiation of Z-bands and myofilament bundles as well as intercalated discs in mouse heart at mid-gestation

  • Version of Record online: 26 January 2024
Description unavailable

PIP5Kγ-immunoreactivity was the highest in the heart at E10. The immunoreactivity gradually weakened in the heart with the prenatal age, and it was at non-significant levels at newborn and postnatal stages. PIP5Kγ-appearance high activity in cardiomyocytes is shifted from the plasma membranes through short and long myofibrils to Z-bands during the mid-term gestation.

Comparative analysis of craniofacial shape in two mouse models of Down syndrome: Ts65Dn and TcMAC21

  • Version of Record online: 24 January 2024
Description unavailable

Our results show that TcMAC21 exhibit similar patterns of craniofacial change to Ts65Dn. However, the Down syndrome-specific morphology is more pronounced in Ts65Dn mice. Our findings reveal the complexity of potential gene interaction in the production of craniofacial phenotypes.

Fibroblast growth factor signalling regulates the development of tooth root

  • Version of Record online: 22 January 2024
Description unavailable

Using in vivo culture system, we demonstrated that FGF18 facilitated the formation of the murine molar roots and periodontal tissues, compared to the control groups which formed ectopic hard tissues at the bottom of the grafted molars. At the early phase of the incubation, FGF18 inhibited the osteogenic gene expression in the mesenchyme of the apical area of the grafted molars, suggesting that Fgf18 may play a role in balancing the skeletal and connective tissue formation during the process of tooth root development.

REVIEW ARTICLES

Open Access

Functional anatomy of the orbit in strabismus surgery: Connective tissues, pulleys, and the modern surgical implications of the “arc of contact” paradigm

  • Version of Record online: 19 January 2024
Description unavailable

The twentieth century heralded a paradigm shift in orbital connective tissue understanding. With advances in anatomical research and imaging techniques, a much clearer picture of the gross anatomy of the EOMs emerged. The arc of contact is not just a static anatomical feature; its length and orientation play a crucial role in determining the effective torque generated by a muscle, thereby influencing the amplitude and direction of eye rotation. Previously overlooked in traditional models, muscle pulleys have emerged as central players in the biomechanics of eye movement.

ORIGINAL ARTICLES

Open Access

Forelimb muscle activation patterns in American alligators: Insights into the evolution of limb posture and powered flight in archosaurs

  • Version of Record online: 19 January 2024
Description unavailable

Electromyographic data from the forelimb muscles of American alligators indicate that alligators modulate the activity patterns of a primary shoulder adductor muscle across a range of limb postures. Among sauropsids, forelimb muscle burst phases from birds and turtles are distinct compared to those of alligators and lizards, suggesting that muscle activation patterns were influenced by major changes in body plan and locomotor modes.

Comparative morphology of oral glands in snakes of the family Homalopsidae reveals substantial variation and additional independent origins of salt glands within Serpentes

  • Version of Record online: 18 January 2024
Description unavailable

We describe interspecific morphological variation in the oral glands of mud snakes. Venom glands range from large to small, while premaxillary glands distinct from the supralabial glands are observed in lineages that underwent a secondary transition to saltwater habitats. Our findings suggest that the differentiated premaxillary glands are likely salt glands that evolved independently three or four times in the family, increasing the number of evolutionary origins of salt glands in snakes.

Open Access

Age-dependent change and intraskeletal variability in secondary osteons of elderly Australians

  • Version of Record online: 18 January 2024
Description unavailable

This study evaluated age-related histomorphometric changes (osteon population density (OPD), osteon area (On.Ar), and Haversian canal area (H.Ar)) in three different bones intra-individually in a modern Australian sample. Femur and humerus histology data were adjusted with robusticity indices, and our findings demonstrate that bone size influences histomorphometry, and this could confound age-at-death estimations that have not been adjusted for robusticity.

The anatomy and feeding mechanism of the Japanese giant salamander (Andrias japonicus)

  • Version of Record online: 12 January 2024
Description unavailable

The Japanese giant salamander (Andrias japonicus) is characterized by a form of suction feeding with unique asymmetric jaw movements. This study revealed that the unique jaw movements are performed by external rotation of the open mandible about its long axis and internal rotation of the closed jaw, with very limited lateral rotation. These movements are permitted by the flexibility of the jaw symphysis and the wide cartilaginous quadrate-articular joint.

Inner ear morphology in wild versus laboratory house mice

  • Version of Record online: 12 January 2024
Description unavailable

The geometry of the semicircular canals of the inner ear was compared between wild-trapped mice, their lab offspring, a typical lab strain and their hybrids. The morphology was conserved among “wild” commensal mice. The release of selection in the laboratory strain allowed for an important morphological divergence, and an increase in the level of fluctuating asymmetry, suggesting the occurrence of drift and decrease of developmental stability.

METHOD

Open Access

ArUco-based stylus reliability for reproductible 3D digitalisation of shoulder cartilage contours

  • Version of Record online: 12 January 2024
Description unavailable

The aim of this study was to assess the inter and intra-observer reproducibility of an ArUco-based localisation stylus to digitalise the glenoid cartilage related to the glenohumeral joint and the contour of the clavicle cartilage related to the acromioclavicular joint. For most parameters, good-to-excellent agreements were observed concerning intra-observer (intra-class correlation [ICC] ranging between 0.81 and 1.00) and inter-observer (ICC ranging between 0.75 and 0.99) reproducibility.

ORIGINAL ARTICLES

Open Access

Population trends in human rib cross-sectional shapes

  • Version of Record online: 10 January 2024
Description unavailable

Detailed rib cross-sectional geometry was extracted from CT scans of 240 adults. PCA shape analysis found significant associations between rib section shape and size with demographic factors (age, sex, height, and weight). These associations produced clear differences in reconstructions of the expected rib cross sections from across a wide variety of demographic groups.

BRIEF COMMUNICATION

Open Access

Oldies, but goldies—preserved morphology and stability of antigenic determinants in decades-old cryosections of human m. vastus lateralis

  • Version of Record online: 07 January 2024
Description unavailable

Immunofluorescent (IF) labelling of cryosections after different storage durations: Slow muscle fibres are depicted in blue (MyHC-I), fast muscle fibres in green (MyHC-IIa), the sarcolemma in red and capillaries in white. These cryosections of human m. vastus lateralis have been stored for 18 years, 66-year old man (a), 9 years, 22-year old man (b) and 2 weeks, 51-year-old woman (c) before IF labelling.

ORIGINAL ARTICLES

Hemispheric asymmetries in cortical grey matter of gyri and sulci in modern human populations from South America

  • Version of Record online: 06 January 2024
Description unavailable

Our results show that directional asymmetry (DA) is the most significant component of interhemispheric variation in cortical volume and area, while the effect of developmental instability has a minor role. Also, interhemispheric differences in a given brain are more significant than those existing among individuals and between sexes. The lack of DA in inferior frontal and precentral regions was confirmed. Gyri and sulci with significant DA were identified, even with DA not reported previously.

Open Access

Vascularization of the gastrointestinal tract of the bottlenose dolphin (Tursiops truncatus, Montagu 1821)

  • Version of Record online: 03 January 2024
Description unavailable

Representative scheme of the gastrointestinal blood supply of the bottlenose dolphin. The duodenum is supplied by multiple duodenal arteries, the pacreaticoduodenal arteries do not supply the pancreas, and the caudal mesenteric artery can originate both from the cranial mesenteric artery or the aorta.

Open Access

Localisation of the centre of the highest region of muscle spindle abundance of anterior forearm muscles

  • Version of Record online: 28 December 2023
Description unavailable

The pronator teres muscle branch of median nerve enters the muscle from the junction of the ulnar head and the humeral head, and after the nerve enters the muscle, an intramuscular nerve dense region is formed in each of these two heads, which are approximately at the level of 25.53 ± 0.31–55.31 ± 0.72% and 12.52 ± 0.29–(37.69 ± 0.38)% of the muscle length, respectively.

Neuronal plasticity in hippocampal neurons due to chronic mild stress and after stress removal in postnatal chicks

  • Version of Record online: 28 December 2023
Description unavailable

The present study evaluates the neuronal plasticity due to chronic mild stress (CMS) and after chronic stress removal (CSR) in hippocampal complex (HCC) of chick. The HCC comprises projection neuron (multipolar and pyramidal), stellate neurons, and four types of spines (filopodia, thin, stubby, and mushroom-shaped spines). In the HCC of 8-week-old chicks, the corrected spine number (N) of the multipolar, pyramidal and stellate neurons significantly decrease due to CMS, but after CSR significant increase was observed. The present study concludes that the environmental changes and even slight modifications in the natural stimuli encounter by the animal must have an effect in their hippocampal region which continuously shows neuronal plasticity.

Organisation of the nervous system in cysts of the freshwater tardigrade Thulinius ruffoi (Parachela, Isohypsibioidea: Doryphoribiidae)

  • Version of Record online: 22 December 2023
Description unavailable

The central and peripheral elements of the nervous system may be observed even after many months of encystment duration. During cyst formation, morphological changes in the nervous system take place. Despite isolating the animals from the environment by enclosing them inside the cuticular capsule, atrophy of the integument-associated sensory fields does not occur. Also, histolysis of the nervous system was not noted, failing to support the controversial claim that histolysis occurs during encystment in tardigrades.

Open Access

The 3D muscle morphology and intramuscular innervation of the digital bellies of flexor digitorum profundus: Clinical implications for botulinum toxin injection sites

  • Version of Record online: 20 December 2023
Description unavailable

The intramuscular innervation and morphology of each of the digital bellies was found to vary. The 3rd, 4th and 5th digital bellies were superficial to the 2nd digital belly and located adjacent to each other. The 2nd digital belly was innervated by the AIN; 3rd digital belly by an intramuscular branch of the AIN from the 2nd belly and the ulnar nerve (UN); 4th digital belly by the UN that continued intramuscularly to supply the 5th digital belly.

Open Access

Prostate-specific antigen: An unfamiliar protein in the human salivary glands

  • Version of Record online: 18 December 2023
Description unavailable

PSA expression was detected in serous cells, among secretory granules (arrows) and in plasma membranes (arrowheads), as well as in striated ducts of both parotid and submandibular glands, supporting salivary glands’ involvement in PSA secretion.

Hindlimb and pelvic anatomy of Caiman yacare (Archosauria, Pseudosuchia): Myology and osteological correlates with emphasis on lower leg and autopodial musculature

  • Version of Record online: 17 December 2023
Description unavailable

The present contribution brings new anatomical information on the hindlimb myology of Caiman yacare in order to shed some light on the knowledge of the crocodylians hindlimb musculature, particularly on the overlooked pedal muscles. The musculoskeletal anatomy is generally conservative in modern crocodylians; however, several differences are present at an interspecific level. This kind of study constitutes the fundamental framework for morphofunctional and macroevolutive interpretations of the archosaur hindlimb.

Three-dimensional freehand ultrasonography to measure muscle volume of the lumbar multifidus: Reliability of processing technique and validity through comparison to magnetic resonance imaging

  • Version of Record online: 12 December 2023
Description unavailable

Three-dimensional freehand ultrasonography can be a valuable method to measure lumbar multifidus volume.The correlation between MRI and 3DfUS measurements of lumbar multifidus volume is moderate to good, and the processing of 3DfUS images to measure LM volume is overall reliable.

LETTERS TO THE EDITOR

ORIGINAL ARTICLES

Ostrich (Struthio camelus) syrinx morphology and vocal repertoire across postnatal ontogeny and sex: Implications for understanding vocal evolution in birds

  • Version of Record online: 06 December 2023
Description unavailable

We describe the anatomy of the syrinx in ostrich for multiple ages and both an adult male and female utilizing dissection and diceCT. We document a small cartilaginous structure at the tracheobronchial juncture present throughout ontogeny. A new auditory dataset of 77 recordings also led to identification of four vocalizations not previously reported in the literature, including the simultaneous production of a hiss and tonal sound.

LETTERS TO THE EDITOR

ORIGINAL ARTICLES

Open Access

Reconstruction of the pelvic girdle and hindlimb musculature of the early tetanurans Piatnitzkysauridae (Theropoda, Megalosauroidea)

  • Version of Record online: 01 December 2023
Description unavailable

Piatnitzkysauridae were Jurassic theropods that represented one of the earliest lineages to have evolved moderate body size. Here, we reconstructed the hindlimb musculature of this clade, allowing a more complete understanding of myological evolution in theropod pelvic appendages.

Open Access

The suprapatellar fat pad: A histotopographic comparative study

  • Version of Record online: 29 November 2023
Description unavailable

Like the infrapatellar fat pad, the suprapatellar fat pad is a white adipose tissue with lobuli and septa. The adipocytes have a smaller area/perimeter/major axis in the suprapatellar fat pad versus the infrapatellar fat pad with a significantly higher amount of collagen type III surrounding the cells in the infrapatellar fat pad group; the septa have comparable elastic fiber content, while collagen type I is higher in the infrapatellar fat pad than in the suprapatellar fat pad and vice-versa for collagen type III. The different morphological compositions determine a major stiffness of infrapatellar fat pad versus suprapatellar fat pad.

BRIEF COMMUNICATION

Open Access

Glial cells are affected more than interneurons by the loss of Engrailed 2 gene in the mouse cerebellum

  • Version of Record online: 27 November 2023
Description unavailable

Engrailed-2 knockout mice (En2−/−) are a model for autism spectrum disorder (ASD), moreover the role of the cerebellum in ASD has been established. In this context, we conducted an immunohistochemical analysis to investigate whether changes in glial and/or interneurons occur in the cerebellum of En2−/− mice compared to wild-type in both males and females.

CORRIGENDUM