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Journal of Anatomy Oct 2023The spatial distribution of the medial gastrocnemius muscle spindles of 10 male and 10 female rats was analysed under a light microscope, and for the first time,...
The spatial distribution of the medial gastrocnemius muscle spindles of 10 male and 10 female rats was analysed under a light microscope, and for the first time, visualised using a 3D model of the muscle. Serial cross-sections of the medial gastrocnemius muscles were separated into 10 divisions along with the proximo-distal axis. The muscle spindles of the rat medial gastrocnemius were predominantly distributed on the proximo-medial divisions of the muscle. There were no sex-related differences in the distribution of the studied receptors. A single division contained an average of 2.71 receptors for animals of both sexes. Moreover, the calculated lengths of male and female rat muscle spindles were comparable, and average lengths did not significantly differ (3.30 ± 1.47 mm for male and 3.26 ± 1.32 mm for female rats). Therefore, the present results fill gaps in recent observations concerning similarities in muscle spindle numbers between male and female animals, despite significant differences in muscle mass and size.
Topics: Rats; Animals; Male; Female; Muscle Spindles; Muscle, Skeletal
PubMed: 37230935
DOI: 10.1111/joa.13895 -
Experimental Physiology Jan 2024
Topics: Muscle Spindles; Mechanotransduction, Cellular; Proprioception; Muscle, Skeletal
PubMed: 38160398
DOI: 10.1113/EP091431 -
ACS Nano Jul 2023The coexistence and interaction of excitatory and inhibitory neurotransmitters at biological synapses enable bilingual communication, serving as a physiological...
The coexistence and interaction of excitatory and inhibitory neurotransmitters at biological synapses enable bilingual communication, serving as a physiological foundation for organism adaptation, internal stability, and regulation of behavior and emotions in mammals. Neuromorphic electronics are expected to emulate the bilingual functions of the biological nervous system for artificial neurorobotics and neurorehabilitation. Here, we have proposed a bilingual bidirectional artificial neuristor array, which utilizes ion migration and electrostatic coupling properties between intrinsically stretchable and self-healing poly(urea-urethane) elastomer and carbon nanotube electrodes, realized by van der Waals integration. The neuristor exhibits depression or potentiation behaviors in response to the same stimulus in different operational phases and achieves a four-quadrant information-processing capability. These properties make it possible to simulate complex neuromorphic processes, which involve bilingual bidirectional responses, such as withdrawal or addiction responses, and array-based automated refresh. Furthermore, the neuristor array is a self-healing neuromorphic electronic device that can function effectively even under 50% mechanical strain and can recover operation voluntarily within 2 h after experiencing mechanical injury. Additionally, the bilingual bidirectional stretchable self-healing neuristor can emulate coordinated neural signal transmission from the motor cortex to muscles and integrate proprioception through strain modulation, similar to the biological muscle spindle. The properties, structure, operation mechanisms, and neurologically integrated functions of the proposed neuristor signify an advancement in neuromorphic electronics for next-generation neurorehabilitation and neurorobotics.
Topics: Animals; Electronics; Synapses; Synaptic Transmission; Elastomers; Proprioception; Mammals
PubMed: 37382222
DOI: 10.1021/acsnano.3c03212 -
Journal of Cutaneous Pathology Sep 2023Schwannomas are benign tumors that arise from the peripheral nerve sheath. Many variants of schwannomas exist, including plexiform, epithelioid, cellular, glandular, and... (Review)
Review
Schwannomas are benign tumors that arise from the peripheral nerve sheath. Many variants of schwannomas exist, including plexiform, epithelioid, cellular, glandular, and ancient. The pseudoglandular subtype is extremely rare, as fewer than five cases of cutaneous pseudoglandular schwannomas have been reported based on our literature review. Herein, we report a case of a 64-year-old female who presented with a skin-colored nodule on her right arm for several years. Histopathology showed a superficial and deep dermal nodulocystic neoplasm composed of epithelioid and spindle cells surrounded by a fibrous stroma. The epithelioid cells surrounded multiple spaces suggestive of glandular differentiation, although many of these spaces also contained serum and red blood cells, raising consideration for vascular differentiation. Multiple epithelial markers, including pancytokeratin and epithelial membrane antigen, were all negative, providing no support for an epithelial tumor with true ductal/glandular differentiation. In addition, CD31, CD34, smooth muscle actin, and desmin stains were negative in these spaces, making a vascular neoplasm or smooth muscle tumor unlikely. However, SOX10 and S-100 stains were positive, including in cells lining the pseudoglandular spaces, supporting the diagnosis of pseudoglandular schwannoma. Complete excision was recommended. This case highlights an extremely rare presentation of the pseudoglandular variant of schwannoma.
Topics: Female; Humans; Middle Aged; Immunohistochemistry; Neurilemmoma; Skin Neoplasms; S100 Proteins; Carcinoma
PubMed: 37312417
DOI: 10.1111/cup.14477 -
Ear, Nose, & Throat Journal Jan 2024Solitary myofibroma or infantile myofibroma is a rare spindle cell neoplasm that generally affects infants before the age of 2 years but cases in young children and...
Solitary myofibroma or infantile myofibroma is a rare spindle cell neoplasm that generally affects infants before the age of 2 years but cases in young children and adults have been described. Although the location of infantile myofibroma in the oral and maxillofacial region has been described, the intramasseteric location of the lesion is very uncommon. A thorough assessment of histopathological and immunohistochemical characteristics is necessary to have a correct diagnosis. Treatment relies on surgical resection. In this article, we present a rare clinical case of a 15-year-old patient with a myofibroma of the masseteric muscle and its management.
PubMed: 38284156
DOI: 10.1177/01455613231223378 -
International Journal of Oral Science Sep 2023Dental primary afferent (DPA) neurons and proprioceptive mesencephalic trigeminal nucleus (MTN) neurons, located in the trigeminal ganglion and the brainstem,...
Dental primary afferent (DPA) neurons and proprioceptive mesencephalic trigeminal nucleus (MTN) neurons, located in the trigeminal ganglion and the brainstem, respectively, are essential for controlling masticatory functions. Despite extensive transcriptomic studies on various somatosensory neurons, there is still a lack of knowledge about the molecular identities of these populations due to technical challenges in their circuit-validated isolation. Here, we employed high-depth single-cell RNA sequencing (scRNA-seq) in combination with retrograde tracing in mice to identify intrinsic transcriptional features of DPA and MTN neurons. Our transcriptome analysis revealed five major types of DPA neurons with cell type-specific gene enrichment, some of which exhibit unique mechano-nociceptive properties capable of transmitting nociception in response to innocuous mechanical stimuli in the teeth. Furthermore, we discovered cellular heterogeneity within MTN neurons that potentially contribute to their responsiveness to mechanical stretch in the masseter muscle spindles. Additionally, DPA and MTN neurons represented sensory compartments with distinct molecular profiles characterized by various ion channels, receptors, neuropeptides, and mechanoreceptors. Together, our study provides new biological insights regarding the highly specialized mechanosensory functions of DPA and MTN neurons in pain and proprioception.
Topics: Animals; Mice; Neurons; Proprioception; Gene Expression Profiling; Pain; Sequence Analysis, RNA
PubMed: 37749100
DOI: 10.1038/s41368-023-00246-z -
The Journal of Physiology Aug 2023Effort perception is widely acknowledged to originate from central processes within the brain, mediated by the integration of an efference copy of motor commands in...
Effort perception is widely acknowledged to originate from central processes within the brain, mediated by the integration of an efference copy of motor commands in sensory areas. However, in this topical review, we aim to challenge this perspective by presenting evidence from neural mechanisms and empirical studies that suggest that reafferent signals from muscle spindles also play a significant role in effort perception. It is now imperative for future research (a) to investigate the precise mechanisms underlying the interactions between the efference copy and reafferent spindle signals in the generation of effort perception, and (b) to explore the potential for altering spindle sensitivity to affect perceived effort during ecological physical exercise and, subsequently, influence physical activity behaviours.
Topics: Muscle Spindles; Brain
PubMed: 37288474
DOI: 10.1113/JP284376 -
Scientific Reports Oct 2023During atherosclerotic plaque formation, smooth muscle cells (SMCs) switch from a contractile/differentiated to a synthetic/dedifferentiated phenotype. We previously...
During atherosclerotic plaque formation, smooth muscle cells (SMCs) switch from a contractile/differentiated to a synthetic/dedifferentiated phenotype. We previously isolated differentiated spindle-shaped (S) and dedifferentiated rhomboid (R) SMCs from porcine coronary artery. R-SMCs express S100A4, a calcium-binding protein. We investigated the role of apelin in this phenotypic conversion, as well as its relationship with S100A4. We found that apelin was highly expressed in R-SMCs compared with S-SMCs. We observed a nuclear expression of apelin in SMCs within experimentally-induced intimal thickening of the porcine coronary artery and rat aorta. Plasmids targeting apelin to the nucleus (N. Ap) and to the secretory vesicles (S. Ap) were transfected into S-SMCs where apelin was barely detectable. Both plasmids induced the SMC transition towards a R-phenotype. Overexpression of N. Ap, and to a lesser degree S. Ap, led to a nuclear localization of S100A4. Stimulation of S-SMCs with platelet-derived growth factor-BB, known to induce the transition toward the R-phenotype, yielded the direct interaction and nuclear expression of both apelin and S100A4. In conclusion, apelin induces a SMC phenotypic transition towards the synthetic phenotype. These results suggest that apelin acts via nuclear re-localization of S100A4, raising the possibility of a new pro-atherogenic relationship between apelin and S100A4.
Topics: Animals; Rats; Apelin; Atherosclerosis; Cell Movement; Cells, Cultured; Myocytes, Smooth Muscle; Phenotype; Swine
PubMed: 37907514
DOI: 10.1038/s41598-023-45470-z -
Experimental Physiology Jan 2024This paper is in two parts: 'There', which is a review of some of the major advances in the study of spindle structure and function during the past 50 years, serving as... (Review)
Review
This paper is in two parts: 'There', which is a review of some of the major advances in the study of spindle structure and function during the past 50 years, serving as an introduction to the symposium entitled 'Mechanotransduction, Muscle Spindles and Proprioception' held in Munich in July 2022; and 'And Back Again', presenting new quantitative morphological results on the equatorial nuclei of intrafusal muscle fibres and of the primary sensory ending in relationship to passive stretch of the spindle.
Topics: Mechanotransduction, Cellular; Muscle Fibers, Skeletal; Muscle Spindles
PubMed: 36628601
DOI: 10.1113/EP090760 -
Experimental Physiology Jan 2024Muscle spindles relay vital mechanosensory information for movement and posture, but muscle spindle feedback is coupled to skeletal motion by a compliant tendon. Little...
Muscle spindles relay vital mechanosensory information for movement and posture, but muscle spindle feedback is coupled to skeletal motion by a compliant tendon. Little is known about the effects of tendon compliance on muscle spindle feedback during movement, and the complex firing of muscle spindles makes these effects difficult to predict. Our goal was to investigate changes in muscle spindle firing using added series elastic elements (SEEs) to mimic a more compliant tendon, and to characterize the accompanying changes in firing with respect to muscle-tendon unit (MTU) and muscle fascicle displacements (recorded via sonomicrometry). Sinusoidal, ramp-and-hold and triangular stretches were analysed to examine potential changes in muscle spindle instantaneous firing rates (IFRs) in locomotor- and perturbation-like stretches as well as serial history dependence. Added SEEs effectively reduced overall MTU stiffness and generally reduced muscle spindle firing rates, but the effect differed across stretch types. During sinusoidal stretches, peak and mean firing rates were not reduced and IFR was best-correlated with fascicle velocity. During ramp stretches, SEEs reduced the initial burst, dynamic and static responses of the spindle. Notably, IFR was negatively related to fascicle displacement during the hold phase. During triangular stretches, SEEs reduced the mean IFR during the first and second stretches, affecting the serial history dependence of mean IFR. Overall, these results demonstrate that tendon compliance may attenuate muscle spindle feedback during movement, but these changes cannot be fully explained by reduced muscle fascicle length or velocity, or MTU force.
Topics: Muscle Spindles; Muscle, Skeletal; Tendons; Movement; Posture
PubMed: 37856330
DOI: 10.1113/EP090872