Journal of Anatomy最新文献

The sentinel lymph node (SN) concept has a significant impact on cancer surgery. We aimed to examine which morphology of dendritic cells (DCs) and macrophages corresponds to "preconditioning" of the SN against cancer. Although macrophages are generally able to tolerate cancer metastasis, the CD169-positive subtype is believed to be a limited exception. Immunohistochemical and morphometric analyses were performed to examine DC-SIGN-, CD68-, and CD169-positive cells in SNs and non-SNs of 23 patients with gastric cancer with or without nodal metastasis. All patients survived for >5 years without recurrence. DCs were present in the subcapsular, paracortical, and medullary sinuses, the endothelia of which expressed DC-SIGN and smooth muscle actin (SMA). In the non-SNs of patients without metastasis, subcapsular DCs occupied a larger area than SNs, and this difference was statistically significant. Conversely, subcapsular DCs were likely to have migrated to the paracortical area of the SNs. DC clusters often overlapped with macrophage clusters; however, histiocytosis-like clusters of CD169-negative macrophages showed a smaller overlap. We found a significantly larger overlap between DC-SIGN and CD169-positive clusters in SNs than in non-SNs; the larger overlap seemed to correspond to a higher cross-presentation of cancer antigens between these cell populations. DC-SIGN-CD169-double positive cells might exist within this overlap. SNs in gastric cancers are usually preconditioned as a frontier of cancer immunity, but they may sometimes be suppressed earlier than non-SNs. DC-SIGN- and CD169-positive cells appeared to decrease owing to a long lag time from the primary lesion occurrence and a short distance from the metastasis.

This study aimed to investigate the incidence of infraorbital canal (IOC) protrusion into the maxillary sinus via computed tomography (CT) and classify its variations. Additionally, it sought to identify nearby sinonasal variations that might elevate the risk of iatrogenic injury. Paranasal sinus CT of 500 patients was evaluated retrospectively. The IOC types were categorized. The length of the IOC, septum, the distance between the maxillary ostium and IOC (dOI), the presence of Haller cells, IOC-related intra-sinus opacity, and IOC dehiscence were investigated. The prevalence of type 3 IOC was 12%, of which 9.2% were type 3c. The maximum length of the IOC was positively correlated with type 3 IOC. A significant difference was found between IOC types in terms of dOI only on the left side. On both sides, the incidence of Haller cells was greater in patients with type 2 IOC than in those with type 1 and in patients with type 3 IOC than in those with type 2. IOC-related opacity and IOC dehiscence were more common in types 2 and 3 IOCs. The assessment of preoperative IOC types and neighboring anatomical structures by CT imaging is of great significance in preventing iatrogenic damage.

The Achilles tendon (AT) is composed of three distinct subtendons, each arising from one of the three heads of the triceps surae muscles: gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and soleus (SOL). These subtendons exhibit a twisted structure, classified as low (Type I), medium (Type II), and high (Type III) twist, based on cadaveric studies. Nevertheless, the in vivo investigation of AT twist is notably scarce, resulting in a limited understanding of its functional significance. The aim of this study was to give insights into the complex 3D AT structure in vivo. A total of 30 healthy participants underwent individual stimulation of each of the triceps surae muscles at rest with the foot attached to the pedal of an isokinetic dynamometer. Ultrasound images were captured to concomitantly examine the displacement of the superficial, middle and deep AT layers. SOL stimulation resulted in the highest AT displacement followed by GM and GL stimulation. Independent of the muscle stimulated, non-uniformity within the AT was observed with the deep layer exhibiting more displacement compared to the middle and superficial layers, hence important inter-individual differences in AT displacement were noticeable. By comparing these individual displacement patterns during targeted stimulations with insights from cadaveric twist classifications on each subtendon area, our classification identified 19 subjects with a 'low' twist and 11 subjects with a 'high' twist. These findings enable us to move beyond cadaveric studies and relate the twisted microstructure of the AT in vivo to its dynamic behaviour.

Kekenodontids are the only known archaeocetes (stem cetaceans) from the late Oligocene. They possess a unique combination of morphological features seen in both more primitive Eocene basilosaurid archaeocetes and more derived Neoceti (mysticetes and odontocetes). However, much remains unknown about the clade, including its acoustic biology. Based on its phylogenetic position crownward to basilosaurids as the latest-diverging archaeocete, we hypothesize that kekenodontids would be specialized for hearing low-frequency sounds. Here, we provide the first report on the cochlear anatomy of a kekenodontid using the holotype of Kekenodon onamata from New Zealand. We compare the cochlear morphology of K. onamata to a sample of extinct and extant cetaceans and quantify shape differences using three-dimensional geometric morphometrics. The analyses show that K. onamata was indeed adapted to hear low frequencies and suggests low-frequency hearing may be a characteristic of raptorial macrophagous fossil cetaceans in contrast to infrasonic bulk filter-feeding mysticetes and ultrasonic echolocating odontocetes.

Bats are unique among mammals for evolving powered flight. However, very little data are available on the muscle properties and architecture of bat flight muscles. Diffusible iodine contrast-enhanced computed tomography (diceCT) is an established tool for 3D visualisation of anatomy and is becoming a more readily accessible and widely used technique. Here, we combine this technique with gross dissection of the Egyptian fruit bat (Rousettus aegyptiacus) to compare muscle masses, fibre lengths and physiological cross-sectional areas (PCSA) of muscles with published forelimb data from an array of non-flying mammals and flying birds. The Egyptian fruit bat has a highly specialised pectoralis (pars posterior) architecturally optimised to generate power. The elbow flexion/extension muscles (biceps brachii and triceps brachii) have comparable PCSAs to the pectoralis, but shorter fibre lengths, which are optimised to generate large forces. Our data also show that the Egyptian fruit bat is more similar to flying birds than non-flying mammals with its highly disparate muscle architecture. Specifically, the Egyptian fruit bat have uniquely enlarged pectoralis muscles and elbow flexion and extension muscles (bicep brachii and triceps brachii) to aid powered flight. Finally, while the Egyptian fruit bat has a comparable heterogeneity in pectoralis (pars posterior) fibre length across the cranial-caudal axis to that seen in birds, the average normalised fibre length is larger than that seen in any of the surveyed birds. Our data here provide a greater understanding of the anatomy and functional specialisation of the forelimb musculature that powers flight.

Although monotremes diverged from the therian mammal lineage approximately 187 million years ago, they retain various plesiomorphic and/or reptilian-like anatomical and physiological characteristics. This study examined the morphology of juvenile and adult female reproductive tracts across various stages of the presumptive oestrous cycle, collected opportunistically from cadaver specimens submitted to wildlife hospitals during the breeding season. In adult females, ovaries had a convoluted cortex with follicles protruding from the ovarian surface. While protruding antral follicles were absent from the ovaries of juvenile echidnas, histological analysis identified early developing primordial and primary follicles embedded into the ovarian cortex. The infundibulum epithelial cells of the oviducts were secretory during the follicular phase but not at other stages, the ampulla region was secretory at all stages and is likely responsible for the mucoid layer deposited around the zona pellucida, and the isthmus region of the oviduct appeared to be responsible for initial deposition of the shell coat, as in marsupials. Female echidnas have two separate uteri, which never merge and enter separately into the urogenital sinus (UGS). This study confirmed that both uteri are functional and increase in glandular activity during the luteal phase. In the juvenile uteri, the endometrium was immature with minimal, small uterine glands. A muscular cervical region at the caudal extremity of each uterus, just before the cranial region of the UGS was defined by the absence of glandular tissue in all female echidnas, including the juveniles. There was no evidence of a definitive vaginal region. A clitoris was also detected that possessed a less developed but similar structural (homologous) anatomy to the male penis; urethral ducts while present did not appear to be patent.

The distribution and amount of intramuscular fat and fibrous tissue can be influenced by biological sex and impact muscle quality in both the functional (force-generating capacity) and morphological (muscle composition) domains. While ultrasonography (US) has proven effective in assessing age- or sex-related differences in muscle quality, limited information is available on sex differences in children. Quantitative ultrasonographic measurements, such as echo intensity (EI), EI bands (number of pixels across 50-unit intervals) and texture, may offer a comprehensive framework for identifying sex differences in muscle composition. The aim of our study was to examine the effect of sex on the rectus femoris (RF) muscle quality in children. We used EI (mean and bands) and texture as muscle quality estimates derived from B-mode US. We hypothesised that RF muscle quality differs significantly between girls and boys. Additionally, we also hypothesised that there is a significant correlation between EI bands and texture. Forty-four non-active healthy children were recruited (n = 22 girls, 12.8 ± 1.5 years; and n = 22 boys, 13.5 ± 1.2 years). RF was assessed using EI mean, EI bands, and texture analysis (homogeneity and correlation) using the Gray-Level Co-Occurrence Matrix. The results revealed significant (p < 0.05) sex differences in RF EI bands and texture. Boys displayed higher values in the 0-50 EI band and had more homogeneous muscle texture than girls. Conversely, girls displayed greater values in the 51-100 EI band and had less homogenous texture compared to boys (p < 0.05). A positive correlation was observed between the 0-50 EI band and muscle homogeneity. However, the 51-100 EI band correlated negatively with homogeneity (p < 0.05), particularly for girls. In conclusion, our study revealed sex-specific differences in mean EI, EI bands, and texture of the RF muscle in children. The variations in the correlations between the first and second EI bands and texture reveal different levels of homogeneity in each band. This indicates that distinct muscle tissue constituents, such as intramuscular fat and/or connective tissue, may be reflected in EI bands. Overall, the methods used in this study may be useful for examining muscle quality in healthy children and those with medical conditions.

Museum specimens are an increasingly important tool for studying global biodiversity. With the advent of diffusible iodine-based contrast-enhanced computed tomography (diceCT), researchers can now visualize an organism's internal soft tissue anatomy without the need for physical dissection or other highly destructive sampling methods. However, there are many considerations when deciding which method of staining to use for diceCT to produce the best gray-scale contrast for facilitating downstream anatomical analyses. The general lack of direct comparisons among staining methodologies can make it difficult for researchers to determine which approaches are most appropriate for their study. Here, we compare the performance of ethylic-Lugol's iodine solution with aqueous-Lugol's staining solution across several vertebrate orders to assess differential imaging outcomes. We found that ethylic-Lugol's is better for visualizing muscle attachment to bone but provides overall lower contrast between soft tissue types. Comparatively, aqueous-based Lugol's provides high-contrast imaging among soft tissue types, although bone is more difficult to discern. We conclude that the choice of staining methodology largely depends on the type of anatomical data the researcher wishes to collect, and we provide a decision-based framework for assessing which staining methodology (ethylic or aqueous) is most appropriate for desired imaging results.

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Cover image: Reconstruction of the human embryo shows that there are only five sets of pharyngeal arches, with the caudal three, as shown in the image, providing the basis for the systemic and pulmonary circulations. See R.H. Anderson et al., ‘Cardiac development demystified by use of the HDBR Atlas’, this issue.

Jaw morphology and function determine the range of dietary items that an organism can consume. Bite force is a function of the force exerted by the jaw musculature and applied via the skeleton. Bite force has been studied in a wide range of taxa using various methods, including direct measurement, or calculation from skulls or jaw musculature. Data for parrots (Psittaciformes), considered to have strong bites, are rare. This study calculated bite force for a range of parrot species of differing sizes using a novel method that relied on forces calculated using the area of jaw muscles measured in situ and their masses. The values for bite force were also recorded in vivo using force transducers, allowing for a validation of the dissection-based models. The analysis investigated allometric relationships between measures of body size and calculated bite force. Additionally, the study examined whether a measure of a muscle scar could be a useful proxy to estimate bite force in parrots. Bite force was positively allometric relative to body and skull mass, with macaws having the strongest bite recorded to date for a bird. Calculated values for bite force were not statistically different from measured values. Muscle scars from the adductor muscle attachment on the mandible can be used to accurately predict bite force in parrots. These results have implications for how parrots process hard food items and how bite forces are estimated in other taxa using morphological characteristics of the jaw musculature.