Increasing the impact of vertebrate scientific collections through 3D imaging: The openVertebrate (oVert) Thematic Collections Network.

The impact of preserved museum specimens is transforming and increasing by three-dimensional (3D) imaging that creates high-fidelity online digital specimens. Through examples from the openVertebrate (oVert) Thematic Collections Network, we describe how we created a digitization community dedicated to the shared vision of making 3D data of specimens available and the impact of these data on a broad audience of scientists, students, teachers, artists, and more. High-fidelity digital 3D models allow people from multiple communities to simultaneously access and use scientific specimens. Based on our multiyear, multi-institution project, we identify significant technological and social hurdles that remain for fully realizing the potential impact of digital 3D specimens.

Comparative neuroimaging of sex differences in human and mouse brain anatomy.

In vivo neuroimaging studies have established several reproducible volumetric sex differences in the human brain, but the causes of such differences are hard to parse. While mouse models are useful for understanding the cellular and mechanistic bases of sex-specific brain development, there have been no attempts to formally compare human and mouse neuroanatomical sex differences to ascertain how well they translate. Addressing this question would shed critical light on the use of the mouse as a translational model for sex differences in the human brain and provide insights into the degree to which sex differences in brain volume are conserved across mammals. Here, we use structural magnetic resonance imaging to conduct the first comparative neuroimaging study of sex-specific neuroanatomy of the human and mouse brain. In line with previous findings, we observe that in humans, males have significantly larger and more variable total brain volume; these sex differences are not mirrored in mice. After controlling for total brain volume, we observe modest cross-species congruence in the volumetric effect size of sex across 60 homologous regions (r=0.30). This cross-species congruence is greater in the cortex (r=0.33) than non-cortex (r=0.16). By incorporating regional measures of gene expression in both species, we reveal that cortical regions with greater cross-species congruence in volumetric sex differences also show greater cross-species congruence in the expression profile of 2835 homologous genes. This phenomenon differentiates primary sensory regions with high congruence of sex effects and gene expression from limbic cortices where congruence in both these features was weaker between species. These findings help identify aspects of sex-biased brain anatomy present in mice that are retained, lost, or inverted in humans. More broadly, our work provides an empirical basis for targeting mechanistic studies of sex-specific brain development in mice to brain regions that best echo sex-specific brain development in humans.

Of mice (dogs, horses, sheep) and men: A novel comparative anatomy dissection course in a United Kingdom university.

At the University of Bristol, we established a novel dissection course to complement our anatomy degree. Students enrolled in this undergraduate course are trained as comparative anatomists, with equal time given to both human and veterinary anatomy. Historically, students opted to dissect either human or veterinary donors as part of the course. To fully reflect the comparative nature of the degree, the dissection course was redesigned so students could dissect both human and veterinary specimens as part of the same course. This facilitated a wide-ranging experience of anatomy, encouraging detailed knowledge of a multitude of species and allowing for multifaceted anatomy graduates to be ready for employment in a wide and competitive job market. Across three iterations of the amended version of the course, median marks ranged from 58.7% to 62.0%, with between 22 and 39 students enrolled. In comparison to the course prior to the introduction of the change, median marks ranged from 59.8% to 62.8%, with between 16 and 24 students enrolled. There was no significant difference between marks before or after the introduction of the concurrently comparative aspect. This paper describes the course, with learning materials and assessments considered, along with some reflection on its value. The course offers benefits to students by widening their perspective on anatomical knowledge and making them more equipped for the job market. It also broadens their understanding of form-function relationships. However, student feedback implied that having the choice between human or veterinary dissection was preferable, and this may outweigh the perceived benefits of the course.

Generalising XTRACT tractography protocols across common macaque brain templates.

Non-human primates are extensively used in neuroscience research as models of the human brain, with the rhesus macaque being a prominent example. We have previously introduced a set of tractography protocols (XTRACT) for reconstructing 42 corresponding white matter (WM) bundles in the human and the macaque brain and have shown cross-species comparisons using such bundles as WM landmarks. Our original XTRACT protocols were developed using the F99 macaque brain template. However, additional macaque template brains are becoming increasingly common. Here, we generalise the XTRACT tractography protocol definitions across five macaque brain templates, including the F99, D99, INIA, Yerkes and NMT. We demonstrate equivalence of such protocols in two ways: (a) Firstly by comparing the bodies of the tracts derived using protocols defined across the different templates considered, (b) Secondly by comparing the projection patterns of the reconstructed tracts across the different templates in two cross-species (human-macaque) comparison tasks. The results confirm similarity of all predictions regardless of the macaque brain template used, providing direct evidence for the generalisability of these tractography protocols across the five considered templates.

Comparative study of the peroneus tertius muscle in pigs based on the origin, course, insertion and innervation.

BACKGROUND: That the peroneus tertius muscle (PT) is a separate entity has been debated. PT has been reported to be part of the extensor digitorum longus muscle, part of the extensor digitorum brevis, or a separate muscle. While pigs have a PT as well as primates, there are no reports of its association with the extensor digitorum longus muscle or extensor digitorum brevis. MATERIALS AND METHODS: In this study, we used gross dissection and Sihler's staining to determine the origin, course, insertion, and innervation of the pig PT. RESULTS: The PT and extensor digitorum longus muscles jointly originated from the femur and ran between the tibialis cranialis and peroneus longus muscles. The PT was inserted at the retinaculum of the metatarsal extensors, tarsal bone, and second metatarsal bone. The branches of the common fibular nerve to the extensor digitorum longus muscle were distributed to the PT. CONCLUSIONS: The innervations suggest that the PT and extensor digitorum longus muscles of the pig were derived from the same muscle mass during development but were named separately due to differences in their morphology. Furthermore, morphological features suggest that pig PT and human PT are probably different muscles.

A new classification of the shoulder girdle muscles in domestic fowl based on their innervation from the brachial plexus.

Many studies have described the muscle anatomy of the domestic fowl (Gallus gallus domesticus), a commonly used animal in developmental experiments. However, some major differences in terminology existed among studies, making it difficult to precisely discuss the muscle homologies between domestic fowl and other animals. In this study, the innervations of shoulder girdle muscles in five sides of the domestic fowl were elucidated and the homology of the shoulder girdle muscles between domestic fowl and other tetrapods was discussed using terminology that conforms to Nomina Anatomica Avium (1993). Unlike previous descriptions, the supracoracoideus, being developed in domestic fowl, is thought to have a different muscular origin from the deltoid muscle. The coracobrachialis cranialis, coracobrachialis caudalis and coracobrachialis muscles, previously described as the coracobrachialis muscle group, had different innervations; the coracobrachialis cranialis should be grouped with the deltoid muscles, and the coracobrachialis caudalis appears to belong to the pectoral muscle group. I propose that the subcoracoscapularis in domestic fowl, keeping the reptilian form, is divided into the subcoracoideus and subscapularis muscles. Based on the innervation, the subscapularis in domestic fowl is homologous with the subscapularis in reptiles and a major part of the subscapularis in mammals. Unlike the descriptions in previous studies, the scapulohumeralis cranialis and caudalis in the domestic fowl in this study, being innervated by the common branch, were found to have a close relationship with the subcoracoscapularis muscle. Based on the observations in this study, a new classification of the shoulder girdle muscles in domestic fowl is proposed.

Bronchial tree of the human embryo: Examination based on a mammalian model.

The symmetry of the right and left bronchi, proposed in a previous comparative anatomical study as the basic model of the mammalian bronchial tree, was examined to determine if it applied to the embryonic human bronchial tree. Imaging data of 41 human embryo specimens at Carnegie stages (CS) 16-23 (equivalent to 6-8 weeks after fertilization) belonging to the Kyoto collection were obtained using phase-contrast X-ray computed tomography. Three-dimensional bronchial trees were then reconstructed from these images. Bronchi branching from both main bronchi were labeled as dorsal, ventral, medial, or lateral systems based on the branching position with numbering starting cranially. The length from the tracheal bifurcation to the branching point of the labeled bronchus was measured, and the right-to-left ratio of the same labeled bronchus in both lungs was calculated. In both lungs, the human embryonic bronchial tree showed symmetry with an alternating pattern of dorsal and lateral systems up to segmental bronchus B9 as the basic shape, with a more peripheral variation. This pattern is similar to that described in adult human lungs. Bronchial length increased with the CS in all labeled bronchi, whereas the right-to-left ratio was constant at approximately 1.0. The data demonstrated that the prototype of the human adult bronchial branching structure is formed and maintained in the embryonic stage. The morphology and branching position of all lobar bronchi and B6, B8, B9, and the subsegmental bronchus of B10 may be genetically determined. On the other hand, no common structures between individual embryos were found in the peripheral branches after the subsegmental bronchus of B10, suggesting that branch formation in this region is influenced more by environmental factors than by genetic factors.

The comparative anatomy of the petrosal bone and bony labyrinth of four small-sized deer.

Here we provide complete 3D reconstructions of the petrosal bone and bony labyrinth of four kinds of small-sized deer (Elaphodus cephalophus, Muntiacus reevesi, Muntiacus muntjak, Hydropotes inermis) based on high-resolution CT scanning, and select one musk deer (Moschus moschiferus) as a comparative object. The petrosal bone and bony labyrinth of E. cephalophus are illustrated for the first time, as well as the petrosal bones of M. reevesi and H. inermis. Some morphological characters of petrosal bone and bony labyrinth can be used to distinguish the above-mentioned species. For example, M. moschiferus shows a prominent transpromontorial sulcus and a ventral basicapsular groove on the petrosal bone; there is a bifurcate cochlear aqueduct on the bony labyrinth of E. cephalophus; there is a distinct fusion between the lateral and posterior semicircular canals on the bony labyrinth of H. inermis. Meanwhile, there are some intraspecific variations on the subarcuate fossa, the tegmen tympani, the cochlear aqueduct, as well as the endolymphatic sac. Our results further confirm that the petrosal bone and bony labyrinth have enormous potential for taxonomy. This work will provide new anatomical data for the phylogenetic study of ruminants in the future, and it will be very practical to identify the isolated ruminants' petrosal bones that are frequently unearthed from paleontological or archeological sites.

A revised terminology for male genitalia in Hymenoptera (Insecta), with a special emphasis on Ichneumonoidea.

Applying consistent terminology for morphological traits across different taxa is a highly pertinent task in the study of morphology and evolution. Different terminologies for the same traits can generate bias in phylogeny and prevent correct homology assessments. This situation is exacerbated in the male genitalia of Hymenoptera, and specifically in Ichneumonoidea, in which the terminology is not standardized and has not been fully aligned with the rest of Hymenoptera. In the current contribution, we review the terms used to describe the skeletal features of the male genitalia in Hymenoptera, and provide a list of authors associated with previously used terminology. We propose a unified terminology for the male genitalia that can be utilized across the order and a list of recommended terms. Further, we review and discuss the genital musculature for the superfamily Ichneumonoidea based on previous literature and novel observations and align the terms used for muscles across the literature.

Zygomatic arch root position in relation to dietary type in haplorhine primates.

The zygomatic root, along with other key craniofacial features, is hypothesized to play a crucial role in strengthening the face in response to stresses and strains related to feeding. As such, it has been cited as indicative of dietary specialization among fossil taxa, although it remains unknown how variable zygomatic arch root position is among living primates, and whether its positioning predicts differences in diet. We test whether primates that consume more mechanically challenging foods possess more anteriorly positioned zygomatic roots compared to those consuming less challenging foods. Zygomatic root position, as defined by the zygomaxillare landmark, was identified and recorded from digital images and physical specimens of adult primate crania. Data were collected from 33 haplorhine species (n = 722). Published data were used to assign species to a dietary type based on patterns of overall consumption along with reliance on especially challenging foods. Pairwise comparisons between mechanically challenging (hard and/or tough) and less mechanically challenging (soft) consumers found significant differences (p < 0.05) in the position of the zygomatic root in 17 of 20 pairs, 11 of which supported the prediction that a more mechanically challenging diet is associated with a more anteriorly placed zygomatic root. PGLS analysis found no significant effect of phylogeny on root position. This suggests that a more anteriorly positioned zygomatic root is useful for identifying dietary specialization in some taxa but is not required for consuming a mechanically challenging diet given that other craniofacial and behavioral factors can facilitate the consumption of such foods.

Comparison of sublingual microcirculatory parameters measured by sidestream darkfield videomicroscopy in anesthetized pigs and adult humans.

BACKGROUND: This study aimed to compare sublingual microcirculatory parameters between anesthetized pigs and conscious adult humans using sidestream darkfield videomicroscopy. The overarching aim of the work was to validate the pig as an experimental model of changes in microcirculatory function following traumatic haemorrhagic shock and resuscitation. METHODS: Fourteen large white pigs and 14 humans were recruited for the study. Sublingual sidestream darkfield videomicroscopy clips were captured in anesthetized pigs and conscious humans. Clips underwent manual analysis in Automated Vascular Analysis 3.2 software. The total vessel density (TVD), perfused vessel density (PVD), proportion of perfused vessels (PPVs) and microvascular flow index (MFI) were quantified. An independent samples t test was used for between species comparison of microcirculatory parameters. RESULTS AND CONCLUSIONS: Conscious humans had a significantly lower TVD, PVD and MFI than anesthetized pigs. No significant difference in PPVs was observed between the species. Perfusion of the microcirculation is a critical determinant of tissue metabolic function and viability. Whilst it may not be surprising that some interspecies differences in the sublingual microcirculatory anatomy were identified between pig and human subjects, it is interesting to report the insignificant difference in PPVs. This direct microcirculatory measure represents a relative change which should hold translatable value across species. We therefore conclude the pig is a suitable model for microcirculatory research and may be a suitable species to investigate changes in microcirculatory perfusion following perturbations in cardiovascular homeostasis, for example during traumatic haemorrhagic shock and resuscitation.

The koala (Phascolarctos cinereus) prostate: a comprehensive histological and immunohistochemical investigation.

The prostate of the koala (Phascolarctos cinereus), and of marsupials more generally, is the primary contributor of seminal fluid, yet comparatively little is known about its microanatomy or biochemistry. This study explored evidence of parenchymal segmentation of the koala prostate. The prostate of three sexually mature koalas were processed for histopathology, histochemistry (Masson's trichrome, Alcian Blue, periodic acid Schiff staining), and immunohistochemistry using basal (tumor protein 63, cytokeratin 14) and luminal (cytokeratin 8/18, prostate specific antigen, androgen receptor) markers. Results confirmed clear segmentation of the koala prostate into three zones, anterior, central, and posterior, characterized by differences in the proportion of glandular tissue, as well as the thickness of collagen fibers; there were also distinct differences in the secretions produced in each zone. Based on immunohistochemistry, the koala prostate showed evidence of both basal proliferative and luminal secretory cells. The ratio of cell types varied across the three segments, with the central segment housing the highest density of basal cells. Globular bodies produced in the anterior zone were shown to possess the same markers as those described for human prostasomes. This study is the first to comprehensively document the marsupial prostate in terms of microanatomy and corresponding immunohistochemistry. While further biochemical analysis, such as proteomics of each segment will better define the relative functions of each tissue, the data presented here are consistent with the hypothesis that the koala prostate potentially represents an example of an ontological stage in the evolutionary differentiation of male eutherian accessory glands.

Comparative anatomy of the mitral valve in four species (human, ovine, porcine and canine): A pre-clinical perspective.

This study aimed to provide comparative anatomical data on the mitral valve and to substantiate the choice between large species for pre-clinical testing of cardiac devices. Different anatomical parameters of the anterior and posterior leaflets, chordae and papillary muscles were measured to characterize the anatomy of the mitral valve in 10 individuals for each four species. Ratios were calculated and used to circumvent the interspecies variations of body and heart size and weight. The results underline many relevant anatomical similarities and differences between man and the three animal species. We confirm that the porcine species is a better model based on anatomical measurements. But many parameters should be considered depending on the shape, size and purpose of the device. The mitral and aortic valve are closer than in man leading to potential damage of the aortic valve by a mitral device. The ovine mitral annulus is more flattened and would sustain more mechanical forces on a round-shaped stent. The anterior and posterior leaflets have comparable height in the animal species leading to more space for implantation. The porcine valve has more chordae allowing less space around the valve for a transcatheter stent. Our observations introduce new comparative data in the perspective of the choice of a large animal model for pre-clinical testing of mitral devices. They are very helpful for all cardiologists, surgeons or engineers who need to understand the reasons for success or failure of a device and to have key elements of discussion.

Osteoderms in a mammal the spiny mouse Acomys and the independent evolution of dermal armor.

Osteoderms are bony plates found in the skin of vertebrates, mostly commonly in reptiles where they have evolved independently multiple times, suggesting the presence of a gene regulatory network that is readily activated and inactivated. They are absent in birds and mammals except for the armadillo. However, we have discovered that in one subfamily of rodents, the Deomyinae, there are osteoderms in the skin of their tails. Osteoderm development begins in the proximal tail skin and is complete 6 weeks after birth. RNA sequencing has identified the gene networks involved in their differentiation. There is a widespread down-regulation of keratin genes and an up-regulation of osteoblast genes and a finely balanced expression of signaling pathways as the osteoderms differentiate. Future comparisons with reptilian osteoderms may allow us to understand how these structures have evolved and why they are so rare in mammals.

Comparative study of pancreatic vessels and mesopancreas of rhesus monkeys and humans.

Introduction: With the introduction of the concept of mesopancreas defining the perineural structures that includes neurovascular bundle and lymph nodes extending from the posterior surface of the pancreatic head to behind the mesenteric vessels,Total Mesopancreas Excision (TMpE) based on this theory has facilitated the development of pancreatic cancer surgery in clinical practice in recent years. However, the existence of so called mesopancreas in the human body is still in debate and the comparative study of mesopancreas of rhesus monkey and human have not been well investigated. Purpose: The aim of our study is to compare the pancreatic vessels and fascia of human and rhesus monkeys in anatomical and embryological perspectives and to support the utilization of rhesus monkey as animal model. Methods: In this study, 20 rhesus monkey cadavers were dissected and their mesopancreas location, relationships and arterial distribution were analyzed. We compared the location and developmental patterns of mesopancreas in macaques and humans. Results: The results showed that the distribution of pancreatic arteries in rhesus monkeys was the same as that in humans, which is consistent with phylogenetic similarities. However, the morphological features of the mesopancreas and greater omentum is anatomically different from that of humans, including (1) the greater omentum is not connected to the transverse colon in monkeys. (2) The presence of the dorsal mesopancreas of the rhesus monkey suggests that it be an intraperitoneal organ. Comparative anatomical studies of mesopancreas and arteries in macaques and humans showed characteristic patterns of mesopancreas and similarities in pancreatic artery development in nonhuman primates, consistent with phylogenetic differentiation.

Evolutionary traces of miniaturization in a giant-Comparative anatomy of brain and brain nerves in Bathochordaeus stygius (Tunicata, Appendicularia).

Appendicularia comprises 70 marine, invertebrate, chordate species. Appendicularians play important ecological and evolutionary roles, yet their morphological disparity remains understudied. Most appendicularians are small, develop rapidly, and with a stereotyped cell lineage, leading to the hypothesis that Appendicularia derived progenetically from an ascidian-like ancestor. Here, we describe the detailed anatomy of the central nervous system of Bathochordaeus stygius, a giant appendicularian from the mesopelagic. We show that the brain consists of a forebrain with on average smaller and more uniform cells and a hindbrain, in which cell shapes and sizes vary to a greater extent. Cell count for the brain was 102. We demonstrate the presence of three paired brain nerves. Brain nerve 1 traces into the epidermis of the upper lip region and consists of several fibers with some supportive bulb cells in its course. Brain nerve 2 innervates oral sensory organs and brain nerve 3 innervates the ciliary ring of the gill slits and lateral epidermis. Brain nerve 3 is asymmetric, with the right nerve consisting of two neurites originating posterior to the left one that contains three neurites. Similarities and differences to the anatomy of the brain of the model species Oikopleura dioica are discussed. We interpret the small number of cells in the brain of B. stygius as an evolutionary trace of miniaturization and conclude that giant appendicularians evolved from a small, progenetic ancestor that secondarily increased in size within Appendicularia.

Striatonigrostriatal connectivity-based cross-species parcellation of human and macaque substantia nigra.

Anatomical and functional heterogeneous substantia nigra (SN) has been extensively studied in humans and animals like rhesus monkeys given its crucial role in modulating a broad range of behaviors. Increasingly important cross-species research of SN may require connectionally homogeneous and homologous subregions of SN as objective and stable starting points from which the evolutionary characteristics of brain could be inspected. However, existing atlases of SN were all inaccurate mappings as a cross-species connectome atlas due to inadequate homology constraint during their constructions, and arbitrary paired use of these atlases might cause unreliable findings. In this study, a reliable blind-source cross-species parcellation of SN was developed based on the following rationale: striatonigrostriatal circuits form major structure of nigral connectivity; different nigral components have unique striatonigrostriatal connectivity; and inter-species corresponding human and macaque nigral components have similar striatonigrostriatal connectivity. Specifically, all voxels in human and macaque SN were grouped together and then classified based on inter-species identically characterized striatonigrostriatal connectivity attributes. Our results delineated a pars compacta-pars reticulate-like parcellation and further demonstrated its reliability by illustrating best-matched whole-brain structural and functional connectivity profiles of inter-species corresponding nigral subregions. Detailed inter-species and inter-regional differences in multi-aspect connectivities of these nigral subregions were inspected. It is expected that this cross-species connectome atlas of SN can offer biologically reliable cornerstones and important information to facilitate future cross-species research.

Anatole-Felix Le Double (1848-1913): 110 years of his death.

Anatole-Félix Le Double was a prominent figure associated with the concept of anatomical variations also including the comprehension of their anthropological and zoological aspects. As an anatomist, Le Double contributed significantly with his major treatise regarding muscles and bony variants. Furthermore, Le Double influenced and popularized paleoanthropology and its relation to anatomy not only in France but in several parts of the world - promoting the idea that anatomical variations are not only surgically and clinically relevant but also have an evolutionary significance. To celebrate 110 years of his passing, this paper aims to explain his trajectory as a young physician to one of the most important figures in how anatomical variants are perceived today.

Two new miniature translucent catfish species of the rare genus Tridens (Siluriformes: Trichomycteridae) from the Madeira River basin, northern Brazil.

Two new miniature species of the trichomycterid genus Tridens are described from the Madeira River drainage, Acre and Rondônia States, Brazil. Until this work, Tridens was a monotypic genus composed solely of Tridens melanops, from the Putumayo/Içá River drainage, upper Amazonas River basin. Tridens vitreus sp.n. is known from upper and middle Madeira River drainage and differs from all other congeners by the lack of pelvic fins and girdle and by vertebra and dorsal-fin ray counts. Tridens chicomendesi sp.n. is known from Abunã River, middle Madeira River drainage and is distinguished from all other congeners by the number of vertebrae, dorsal-fin ray count and anal-fin base colouration pattern. Tr. chicomendesi sp.n. is further distinguished from T. vitreus by a combination of character states regarding the position of urogenital opening, dorsal-fin position, anal-fin position, maxillary barbel length, number of premaxillary teeth, number of dorsal-fin rays, number of anal-fin rays, number of lateral-line system pores, frontal bone anatomy, degree of ossification of maxilla, anatomy of quadrate-hyomandibular joint, size of posterodorsal process of hyomandibula, length of opercular patch of odontodes, number of interopercular odontodes, proportion of upper hypural plate cartilage relative to its area ; by the absence of a proximal, distal and ventral cartilages on ventral hypohyal; by the absence of a lateral process on basibranchial 4; by the presence of a cartilage block on the lateral process of autopalatine, the presence of a well-developed ossification on proximal margin of ventral hypohyal, the presence of hypobranchial foramen; and by the presence of an anterior cartilaginous joint between quadrate and base of posterodorsal process of hyomandibula. This work represents the first species description for the subfamily Tridentinae in more than 30 years and for the genus Tridens since its original description in 1889.