Anatomical record (Hoboken, N.J. : 2007)最新文献

{"title":"Human evolution and the obstetrical dilemma: The pelvic floor hypothesis.","authors":"Barbara Fischer, Ekaterina Stansfield","doi":"10.1002/ar.70279","DOIUrl":"10.1002/ar.70279","url":null,"abstract":"<p><p>Human childbirth is mechanically difficult because a large-headed, broad-shouldered fetus must pass through a comparatively narrow, twisted bony birth canal. Traditional explanations of this \"obstetrical dilemma\" emphasize the role of bipedal locomotion in inhibiting the evolution of a wider, more spacious pelvis. Yet recent evidence suggests that additional selective pressures shaped human pelvic anatomy. The pelvic floor hypothesis proposes that expansion of the bony birth canal would compromise the pelvic floor's stability by increasing the distance over which it must span to support the lower abdominal organs. Here, we summarize comparative, clinical, and population-based empirical evidence, as well as findings from biomechanical modeling studies, in order to evaluate the pelvic floor hypothesis. Across mammals, pelvic canal shape and size covary with posture and gravitational loading. In humans, wider and more mediolaterally expanded pelves are consistently associated with an increased risk of pelvic floor disorders, while biomechanical models show disproportionate increases in pelvic floor deformation and tissue stress with increasing canal width. Evidence that pelvic floor disorders can reduce biological fitness supports their evolutionary relevance. Together, these findings identify pelvic floor stability as an important and previously underappreciated factor constraining the evolution of the human pelvis.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148440569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional implications of ear loss in sand lizards.","authors":"Kelsey M Jenkins, Kevin de Queiroz","doi":"10.1002/ar.70284","DOIUrl":"https://doi.org/10.1002/ar.70284","url":null,"abstract":"<p><p>Despite being a highly advantageous trait, tympanic hearing was secondarily lost multiple times within tetrapods. Typically, loss of a sensory structure implies a shift to new environments where selection for another trait inhibits the development of said sensory structure, or a relaxation of selection on the sensory organ. However, the loss of tympanic hearing within North American sand lizards (Phrynosomatidae: Callisaurini) has eluded explanation. To explore the evolutionary reduction and loss of tympanic hearing within this clade, we created 3D models of the stapes to analyze morphological differences. Then, we determined if those morphological differences impact stapedial movement using harmonic response analysis (HRA). We also included the stapes of the callisaurin sand lizards along with those of a diversity of other squamatans in a series of linear discriminant analyses to determine if stapes of tympanic and atympanic species differ morphologically, and if the presence or absence of limbs, lifestyle, or diet influence stapedial morphology. We found that both earless taxa (Cophosaurus, Holbrookia) possess stapes that are relatively short with a large footplate, similar to those of other atympanic squamatans, while the eared taxon Uma has a long and slender stapes, similar to those of other tympanic squamatans. However, the eared taxon Callisaurus possesses a stapes that is intermediate between those of Uma and the atympanic species. Similarly, it was less prone to displacement within the HRA than other eared species. We found that neither lifestyle nor diet could explain differences in ear morphology within this clade. This suggests that ear loss in this clade is either due to a relaxation of selection on the ear, or more likely, differences in substrate use when the lizards bury themselves resulted in selection on the ear that influences both stapedial shape and tympanum loss, perhaps for the transmission of low-frequency vibrations through substrate. The combination of a tympanum with a broad stapes in Callisaurus, in the context of the other sand lizard genera, suggests that modification to the stapes and quadrate may precede the formation or loss of a tympanum, which has implications for interpreting the evolutionary origins of hearing from fossils.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148440595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphophysiological dynamics of the proximal post-testicular ducts in Crotalus durissus Linnaeus, 1758 (Squamata: Viperidae).","authors":"Flávia Cappuccio de Resende, Gustavo Caldeira Cotta, Clara d' Ávila Fonseca Paiva de Paula Freitas, Leonardo Carvalho, Heloísa Helena Marques Oliveira, Victória Gomes Carvalho Silva, Lívia de Fátima Moreira Silva, Luciana Maria Silva, Samyra Maria Dos Santos Nassif Lacerda, Guilherme Mattos Jardim Costa","doi":"10.1002/ar.70287","DOIUrl":"https://doi.org/10.1002/ar.70287","url":null,"abstract":"<p><p>The organization and function of reptilian excurrent ducts remain poorly characterized, particularly in Neotropical snakes. We provide the first integrative morphological, histochemical, immunohistochemical, and ultrastructural analysis of the proximal post-testicular ducts of Crotalus durissus across reproductive stages. Using light, transmission electron, and confocal laser microscopy, we examined the rete testis, ductuli efferentes, ductuli epididymides, and ductus epididymis of adult males. The proximal post-testicular ducts are contained within the epididymal sheath alongside the adrenal gland. No anatomical regionalization was identified along the epididymis. The ductuli efferentes exhibited cuboidal epithelium with stereocilia-like projections, while the ductuli epididymides displayed simple columnar epithelium with abundant periodic acid-Schiff (PAS) and Bromophenol Blue (BB) positive secretory granules. The ductus epididymis consisted of pseudostratified epithelium with principal, basal, and clear cells. Confocal analyses revealed wheat germ agglutinin (WGA) in principal cells of the ductus epididymis and Concanavalin A (ConA) positive secretory granules in ductuli epididymides. Aquaporin-9 immunolabeling was detected in the epithelium of the ductus epididymis and ductuli efferentes, suggesting a role in luminal fluid regulation. Ultrastructural observations of the ductus epididymis revealed extensive rough endoplasmic reticulum, Golgi complexes, microvilli, and phagolysosomes in principal cells, supporting secretory, absorptive, and phagocytic functions. Seasonal variation was evident, with snakes in testicular activity exhibiting hypertrophy of all components analyzed. Collectively, our findings indicate that these ducts of C. durissus are functionally specialized for secretion and absorption, rather than sperm storage, thereby contributing to the establishment and regulation of a luminal microenvironment essential for sperm maturation in this seasonally reproducing viperid.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148431835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The mechanism of labor in nonhuman primates: A look inside.","authors":"Melissa K Stoller","doi":"10.1002/ar.70243","DOIUrl":"https://doi.org/10.1002/ar.70243","url":null,"abstract":"<p><p>While in humans, the flexed position of the fetus and its rotating course down the birth canal are well documented, in other primates the mechanism of labor is unknown. Despite the lack of comparative data, it is commonly assumed that the human obstetric mechanism is unique, and anthropologists have disputed when and why the transition to the modern human mechanism occurred. The purpose of this study is to establish the mechanism of labor in two species of nonhuman primates. The data in this study consist of a series of radiographs taken throughout labor in unanesthetized, unrestrained, spontaneously laboring Papio anubis (n = 4) and Saimiri boliviensis (n = 7), pelvimetric radiographs, and neonatal cephalometry. In both species, the fetus normally presents in extension, with the face or brow dilating the cervix, and the head being delivered with the mentum anterior. Contra popular assumption, fetal rotation during labor was observed, and was analogous to rotation in human face presentations. Dramatic pelvic deformation, but not fetal head molding, was recorded. I suggest that previously published cephalopelvic ratios of nonhuman primates do not accurately represent the obstetric situation. Here, measurements of the actually constrictive diameters of the nonhuman primate pelvis and functionally significant measures of the fetal head are presented. The implications of this study for the obstetric evaluation of fossil hominid pelves are discussed.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148414576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SOX6 is expressed in various cell lineages in the developing mouse heart and contributes to proper valvuloseptal development.","authors":"Hannah G Tarolli, Andrew B Harvey, Inara Devji, Raymond N Deepe, Jenna R Drummond, Renélyn A Wolters, Andy Wessels","doi":"10.1002/ar.70285","DOIUrl":"10.1002/ar.70285","url":null,"abstract":"<p><p>Cells derived from the endocardium, epicardium, cardiac neural crest, and second heart field play a critical role in the formation of the valvuloseptal structures of the heart. Previous studies have shown that the expression of the transcription factor SOX9 in these cell populations is essential in the regulation of this process. SOX9 interacts with other SOX family members including SOX5 and SOX6 to cooperatively regulate other developmental events. Although SOX6 has documented roles in the postnatal heart, its role in cardiac development has not yet been examined. For the current study we decided to investigate the importance of SOX6 in valvuloseptal morphogenesis. Expression studies revealed that SOX6 is expressed in many of the cell lineages that contribute to the formation of the heart. Given the pattern of SOX6 expression in the endocardium and endocardial-derived cells as well as in the coronary endothelium, we focused on the role of SOX6 in these cell populations by generating endothelial/endocardial-specific Sox6 knockout mice. These conditional knockout mice presented with ventricular septal defects, enlarged atrioventricular valves, and coronary abnormalities. Cardiovascular defects observed in the endothelial/endocardial-specific Sox6 knockout mouse demonstrate that SOX6 plays an important role in valvuloseptal development.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13617672/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148414562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How does the inner structure of the limb bones of aquatic birds relate to their locomotor abilities?","authors":"Martin Segesdi, Alexandra Houssaye","doi":"10.1002/ar.70282","DOIUrl":"https://doi.org/10.1002/ar.70282","url":null,"abstract":"<p><p>Aquatic birds encompass diverse ecologies and locomotion types. Some of them are flightless; others lack effective terrestrial locomotion, whereas numerous species perform well in water, on land, and in the air. Bone microanatomy provides insight into bone functional adaptations to different locomotor strategies. Previous studies on aquatic birds have relied mainly on 2D transverse sections. In this study, we aim to qualitatively and quantitatively analyze the microanatomical characteristics of limb long bones using several virtual sectional planes and whole-bone measurements to investigate in more detail the link between inner structure and locomotor abilities. In the humerus, femur, and tibiotarsus, whole bone compactness is higher in species with better diving abilities, likely reflecting adaptations to counteract buoyancy and drag. In these bones, flightless penguins exhibit the highest compactness, consistent with the release from flight-related constraints. The tarsometatarsus shows a distinct pattern and is more compact in foot-propelled and less terrestrial birds, whereas non-foot-propelled, terrestrial penguins show a lower compactness than in their other bones. Trabecular structure and orientation in the humerus appear to reflect general wing kinematics and wing-propelled locomotion, while hindlimb bones show structural traits probably related to body weight support and foot-propelled swimming. These findings contribute to a better understanding of the adaptations of the birds' skeletal system to various lifestyles and could prove useful in inferring the ecology of extinct species.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148414625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relative performance of automated fiber-tracking approaches to 3D muscle architecture and their utility for comparative biomechanics.","authors":"Christopher M Zobek, Kevin M Middleton, Casey M Holliday","doi":"10.1002/ar.70281","DOIUrl":"https://doi.org/10.1002/ar.70281","url":null,"abstract":"<p><p>Muscle architecture is a key determinant of muscle performance, informing the calculation of functional traits such as force production and excursion distance. Due to its importance in understanding vertebrate biomechanics and ecology, several methods have been developed for reconstructing muscle fascicle architecture from CT and other contrast imaging data. Two automated methods have gained prominence and have been widely applied across vertebrate taxa: the Xfiber extension for the commercial Avizo/Amira software and the Goodfibes R package. Here, we present a comparison of muscle fascicle reconstructions using Xfiber and Goodfibes across a variety of CT datasets varying in muscle morphology and data quality to test the comparative performance of each method. We compared fiber length, fiber orientation, and fiber tortuosity/curvature results for each method across all datasets, with the first published comparison of orientation measurements between the two software packages. We found that Xfiber and Goodfibes produced broadly similar fiber length and orientation measurements across high quality datasets, but Goodfibes results diverged at lower resolutions and could not follow highly curved muscle fascicles. Tortuosity/curvature measurements were more divergent between the two tools, partially as a result of differing filtering methods. Ultimately, we find both methods to be highly promising for future comparative studies, though Goodfibes users will need to be slightly more considerate of data quality and muscle morphology.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148407709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PNA-lectin histochemistry shows putative epidermal cells secreting antifreeze glycoproteins (AFGPs) in the Antarctic fish Trematomus bernacchii (Boulenger, 1902).","authors":"Lorenzo Alibardi, Chiara Maria Motta","doi":"10.1002/ar.70283","DOIUrl":"https://doi.org/10.1002/ar.70283","url":null,"abstract":"<p><p>The epidermis of fish species which inhabit the frigid waters of the Antarctic realm can be expected to form a protective thermal barrier around them, involving their epidermis. The present study, mainly using lectin-histochemistry, identifies in the epidermis of the Antarctic fish Trematomus bernacchii the presence of numerous cells that secrete likely antifreeze glycoproteins (AFGPs) for thermic protection from extremely cold water. The PNA-FITC conjugated lectin recognizes the known galactosyl-N-acetylgalactosamine disaccharide that forms the long repetitive glycidic units of the AFGPs. The mucus-secreting cells represent 3.1% average of total epidermal cells, are evenly distributed in the epidermis and their secretion is mainly discharged on the epidermal surface, contributing to the formation of the secreted mucus cuticle. Furthermore, the AFGPs are positive for glycoprotein/glycolipid production in the epidermis, as indicated by general histochemical and ultrastructural methods, namely Blue Nile Sulphate and silver-methenamine reactions. Lipid material likely derives from the differentiating keratinocytes during their movement toward the epidermal surface where they are eventually desquamated. Some AFGPs are present with a diffuse distribution also in the dermis. The study indicates that not only AFGPs but also some lipids likely effectively protect the epidermis that is the first tissue in contact with the cold marine waters of Antarctica.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148393139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracheal chambers as a key innovation for high-frequency emission in bat echolocation.","authors":"Nicolas L M Brualla, Laura A B Wilson, Khizar Hayat, Michael Doube, Vuong Tan Tu, Thongchai Ngamprasertwong, Thanakul Wannaprasert, Daisuke Koyabu","doi":"10.1002/ar.70266","DOIUrl":"https://doi.org/10.1002/ar.70266","url":null,"abstract":"<p><p>Key innovations are pivotal for biodiversity and facilitating evolutionary success, enabling organisms' adaptation to various ecological niches through the diversification of phenotypic traits. In mammals, notable adaptations include evolving hypsodonty for grazing on grasses and, for bats, evolving echolocation and wing acquisition. Recent studies have highlighted the overlooked morphological diversity of the bat larynx, a key organ for echolocation capabilities. Tracheal chambers, found on the trachea's first rings, are enigmatic components within the laryngeal complex whose origins and functions remain incompletely understood. We hypothesized that these structures demonstrate evolutionary convergence and represent a key innovation responsible for the diversification of laryngeal echolocation behaviors. By analyzing 51 bat species, their laryngeal cartilages, and tracheal chambers, we explored relationships between body mass, sound frequencies, and chamber volumes. We hypothesized that tracheal chambers likely facilitated laryngeal echolocation capabilities in bats. Ancestral state reconstructions were conducted to understand the evolution of tracheal chambers and echolocation behaviors in bats. We conclude that tracheal chambers might support higher frequency sound production and could have been pivotal for high-duty cycle echolocation specialization during the development of nasally emitted calls, which allowed bats to thrive in diverse environments. We suggest that tracheal chambers are specialized phenotypic adaptations that might have helped in diversifying laryngeal echolocation behaviors and the evolutionary success of bats.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148400388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cytoarchitectural and immunohistochemical characterization of calbindin and parvalbumin from the primary motor cortex of the marmoset (Callithrix jacchus).","authors":"Luís Marcos M Guerra, Paulo Leonardo A G Morais, Gabriel S Rocha, Mariana G Guerra, Adalberto V Costa, Expedito S Nascimento-Júnior, Rovena C G J Engelberth, Jeferson S Cavalcante, Paul R Manger, José Rodolfo L P Cavalcanti","doi":"10.1002/ar.70267","DOIUrl":"https://doi.org/10.1002/ar.70267","url":null,"abstract":"<p><p>The primary motor cortex (M1) contains specialized neurons involved in planning and initiating voluntary movements. Calcium-binding proteins (CBP) play a crucial role in modulating and promoting neuronal plasticity by buffering intracellular calcium. CBP are found in distinct neuronal subpopulations, knowledge of which can improve the understanding of locomotion networks. The marmoset monkey is an increasingly popular animal model for studying the neural basis of voluntary movement. Thus, understanding the structural and functional differences in the cortical motor system of marmosets compared to humans is necessary to fully appreciate the parallels and differences between model and target organisms. We analyzed the cytoarchitecture of neurons containing CBP calbindin (CB) and parvalbumin (PV) in marmoset M1. Marmoset M1 is a homogeneous agranular territory that emphasizes structures in layer V. Using visual contrast methodology, we observed stronger CB immunoreactivity (CBir) within layers I to III, while layers II, III, and V show greater PV immunoreactivity (PVir). CBir revealed a higher cell density in layer II and the presence of halo cells in layer V, while PVir revealed higher cell densities in layers II, III, and V, with PVir neurons being generally larger than CBir neurons. Based on these results, we can conclude that CBP immunostaining allows for the characterization of M1. Variations in laminar distribution suggest functional heterogeneity of the CBP-containing neurons in the cortical circuit.</p>","PeriodicalId":520555,"journal":{"name":"Anatomical record (Hoboken, N.J. : 2007)","volume":" ","pages":""},"PeriodicalIF":2.1,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148393130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}