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Frontiers in Neuroanatomy 2021Afferent neurons and their mechanoreceptors provide critical sensory feedback for gait. The anatomical distribution and density of afferents and mechanoreceptors...
Afferent neurons and their mechanoreceptors provide critical sensory feedback for gait. The anatomical distribution and density of afferents and mechanoreceptors influence sensory feedback, as does mechanoreceptor function. Electrophysiological studies of hind paw skin reveal the different types of afferent responses and their receptive fields, however, the anatomical distribution of mechanoreceptor endings is unknown. Also, the role of integrin α1β1 in mechanoreceptor function is unclear, though it is expressed by keratinocytes in the stratum basale where it is likely involved in a variety of mechanotransduction pathways and ion channel functionalities. For example, it has been shown that integrin α1β1 is necessary for the function of TRPV4 that is highly expressed by afferent units. The purpose of this study, therefore, was to determine and compare the distribution of mechanoreceptors across the hind paw skin and the footfall patterns of -null and wild type mice. The -null mouse is lacking the integrin α1 subunit, which binds exclusively to the β1 subunit, thus rendering integrin α1β1 nonfunctional while leaving the numerous other pairings of the β1 subunit undisturbed. Intact hind paws were processed, serially sectioned, and stained to visualize mechanoreceptors. Footfall patterns were analyzed as a first step in correlating mechanoreceptor distribution and functionality. Merkel cells and Meissner-like corpuscles were present, however, Ruffini endings and Pacinian corpuscles were not observed. Meissner-like corpuscles were located exclusively in the glabrous skin of the footpads and digit tips, however, Merkel cells were found throughout hairy and glabrous skin. The increased density of Merkel cells and Meissner-like corpuscles in footpads 1 and 3 and Meissner-like corpuscles in footpad 4 suggests their role in anteroposterior balance, while Meissner-like corpuscle concentrations in digits 2 and 5 support their role in mediolateral balance. Finally, a larger density of Meissner-like corpuscles in footpads 3 and 4 in male -null mice compared to wild type controls paves the way for future site-specific single fiber recordings to provide insight into the role of integrin α1β1 in tactile mechanotransduction.
PubMed: 33737870
DOI: 10.3389/fnana.2021.628711 -
Journal of Microscopy and Ultrastructure 2022The cell is the basic structural unit of all living organisms. Most of the cells forming the human body share the basic components, but there are many categories that... (Review)
Review
The cell is the basic structural unit of all living organisms. Most of the cells forming the human body share the basic components, but there are many categories that have specific light and electron microscopic characteristics. This review shed a light on these cell categories and their morphologies. Stem cell category is the cells responsible for the regeneration of damaged or lost cells, whereas protein-secreting cells are those responsible for the production and secretion of proteins. Protein-secreting cells have specific characters such as basophilic cytoplasm and vesicular nucleus by light microscope; these are confirmed by an electron microscope that shows rough endoplasmic reticulum, Golgi apparatus, secretory granules, and mitochondria. Steroid secreting, ion transporting, and contracting categories have specific morphology. Phagocytic cells such as macrophages and neutrophils are characterized by the presence of many lysosomes and phagosomes. Supporting cells are very important category as they not only support but also usually have another function such as myelin formation in Schwann, blood-brain barrier in astrocytes, or modification of response as in Pacinian corpuscle. Many cells showed interrelated characters between different categories, for example, phagocytic cells are able to contract to perform their function in fighting microorganism. Although we have trillions of cells, yet they only fall in some categories. Each cell category has specific morphological characters confirmed by ultrastructural characters. They all adapted to perform the desired functions.
PubMed: 35832316
DOI: 10.4103/jmau.jmau_74_20 -
Journal of Anatomy Jul 2021Vibration is detected by mechanoreceptors, including Pacinian corpuscles (PCs), which are widely distributed in the human body including the adventitia of large blood...
Vibration is detected by mechanoreceptors, including Pacinian corpuscles (PCs), which are widely distributed in the human body including the adventitia of large blood vessels. Although the distribution of PCs around large limb vessels has been previously reported, there remains no consensus on their distribution in the adventitia of the human deep blood vessels in the upper arm. In addition, the physiological functions of PCs located around the deep limb blood vessels remain largely unknown. This study aimed to elucidate detailed anatomical features and physiological function of lamellar sensory corpuscles structurally identified as PCs using the immunohistochemical methods around the deep vessels in the upper arm. We identified PCs in the connective tissue adjacent to the deep vessels in the upper arm using histological analysis and confirmed that PCs are located in the vascular sheath of the artery and its accompanying vein as well as in the connective tissue surrounding the vascular sheath and nerves. PCs were densely distributed on the distal side of deep vessels near the elbow. We also examined the relationship between vascular sound and pulsating sensation to evaluate the PCs functions around deep arteries and veins and found that the vascular sound made by pressing the brachial arteries in the upper arm was associated with the pulsating sensation of the examinee. Our results suggest that PCs, around deep vessels, function as bathyesthesia sensors by detecting vibration from blood vessels.
Topics: Aged, 80 and over; Arm; Arteries; Female; Humans; Male; Pacinian Corpuscles; Pulsatile Flow
PubMed: 33527396
DOI: 10.1111/joa.13398 -
Surgical and Radiologic Anatomy : SRA Jul 2021Fast-adapting afferent input from the sole Pacinian corpuscles (PCs) is essential for walking. However, the distribution of PCs in the plantar subcutaneous tissue...
INTRODUCTION
Fast-adapting afferent input from the sole Pacinian corpuscles (PCs) is essential for walking. However, the distribution of PCs in the plantar subcutaneous tissue remains unknown.
MATERIALS AND METHODS
Using histological sections tangential to the plantar skin of eight near-term fetuses, we counted 528-900 PCs per sole.
RESULTS
Almost half of the sole PCs existed at the level of the proximal phalanx, especially on the superficial side of the long flexor tendons and flexor digitorum brevis. Conversely, the distribution was less evident on the posterior side of the foot. The medial margin of the sole contained fewer PCs than the lateral margin, possibly due to the transverse arch. In contrast to a cluster formation in the anterior foot, posterior PCs were almost always solitary, with a distance greater than 0.5 mm to the nearest PC.
DISCUSSION AND CONCLUSION
Because a receptive field of PCs is larger than that of the other receptors, fewer solitary PCs might cover the posterior sole. In infants, the amount of anterior sole PCs seemed to determine the initial walking pattern using the anterior foot without heel contact. Anterior PCs concentrated along flexor tendons might play a transient role as tendon organs during the initial learning of walking. During a lesson in infants, mechanical stress from the tendon and muscle was likely to degrade the PCs. In the near term, the sole PCs seemed not to be a mini-version of the adult morphology but suggested an infant-specific function.
Topics: Female; Fetus; Foot; Gait; Humans; Male; Pacinian Corpuscles; Standing Position; Subcutaneous Tissue
PubMed: 33471166
DOI: 10.1007/s00276-021-02685-x -
Journal of Clinical Medicine Jan 2021Sensory corpuscles of human skin are terminals of primary mechanoreceptive neurons associated with non-neuronal cells that function as low-threshold mechanoreceptors.... (Review)
Review
Sensory corpuscles of human skin are terminals of primary mechanoreceptive neurons associated with non-neuronal cells that function as low-threshold mechanoreceptors. Structurally, they consist of an extreme tip of a mechanosensory axon and nonmyelinating peripheral glial cells variably arranged according to the morphotype of the sensory corpuscle, all covered for connective cells of endoneurial and/or perineurial origin. Although the pathologies of sensitive corpuscles are scarce and almost never severe, adequate knowledge of the structure and immunohistochemical profile of these formations is essential for dermatologists and pathologists. In fact, since sensory corpuscles and nerves share a basic structure and protein composition, a cutaneous biopsy may be a complementary method for the analysis of nerve involvement in peripheral neuropathies, systemic diseases, and several pathologies of the central nervous system. Thus, a biopsy of cutaneous sensory corpuscles can provide information for the diagnosis, evolution, and effectiveness of treatments of some pathologies in which they are involved. Here, we updated and summarized the current knowledge about the immunohistochemistry of human sensory corpuscles with the aim to provide information to dermatologists and skin pathologists.
PubMed: 33435193
DOI: 10.3390/jcm10020227 -
Journal of Pediatric Urology Apr 2021Circumcision is a common procedure. Recently, tissue-sparing approaches have become a matter of interest, and a nerve-sparing approach is described in adults. Although...
BACKGROUND
Circumcision is a common procedure. Recently, tissue-sparing approaches have become a matter of interest, and a nerve-sparing approach is described in adults. Although circumcision is common in the practice, the nerve-sparing approach has not been evaluated in the pediatric age group.
OBJECTIVE
To give a contemporary evaluation of the preputium histology, challenge the phenomenon of a genuine nerve-sparing approach, and report the results of a prospective cohort contrasting the tissue-sparing fine dissection technique to the regular sleeve circumcision in the pediatric age group.
STUDY DESIGN
A total of 20 healthy children between 7 and 12 years of age were enrolled in the study. All circumcisions were carried out for religious purposes, and children with any anatomical anomaly, skin lesions, or Balanitis Xerotica Obliterans were not included in the study. The first 10 children underwent regular sleeve circumcision, while the latter 10 children underwent tissue-sparing fine dissection modification of the sleeve technique. All materials obtained from the circumcision were examined by a single pathologist, and relevant tissue structures were counted and compared between the groups.
RESULTS
Both techniques were satisfactory in terms of final cosmetic results, without significant complications, such as bleeding, massive edema, iatrogenic chordee, or unacceptable cosmetics. None of the children required readmission or medical intervention other than analgesics and topical moisturizing creams. Preservation of all nervous system structures, including the receptors, appeared to be not possible with macroscopic dissection techniques due to micrometer scale depth of the touch receptors. Nerve trunks were also located in less than 1-mm depth. The tissue-sparing technique could preserve significantly more vascular structures, nerve trunks, and Pacinian Corpuscles, which can be a matter of further long-term research.
CONCLUSION
We propose the term "tissue-sparing" instead of "nerve-sparing" for the available techniques. The tissue-sparing technique did not affect the clinical outcomes and the postoperative course in our study. However, it showed to be superior in terms of preserving the vascular structures, nerve trunks, and Pacinian Corpuscles.
Topics: Adult; Balanitis Xerotica Obliterans; Child; Circumcision, Male; Foreskin; Humans; Lichen Sclerosus et Atrophicus; Male; Prospective Studies
PubMed: 33339734
DOI: 10.1016/j.jpurol.2020.11.040 -
Science Advances Dec 2020The skin covering the human palm and other specialized tactile organs contains a high density of mechanosensory corpuscles tuned to detect transient pressure and...
The skin covering the human palm and other specialized tactile organs contains a high density of mechanosensory corpuscles tuned to detect transient pressure and vibration. These corpuscles comprise a sensory afferent neuron surrounded by lamellar cells. The neuronal afferent is thought to be the mechanical sensor, whereas the function of lamellar cells is unknown. We show that lamellar cells within Meissner and Pacinian corpuscles detect tactile stimuli. We develop a preparation of bill skin from tactile-specialist ducks that permits electrophysiological recordings from lamellar cells and demonstrate that they contain mechanically gated ion channels. We show that lamellar cells from Meissner corpuscles generate mechanically evoked action potentials using R-type voltage-gated calcium channels. These findings provide the first evidence for R-type channel-dependent action potentials in non-neuronal cells and demonstrate that lamellar cells actively detect touch. We propose that Meissner and Pacinian corpuscles use neuronal and non-neuronal mechanoreception to detect mechanical signals.
PubMed: 33328243
DOI: 10.1126/sciadv.abe6393 -
Sensors (Basel, Switzerland) Dec 2020It is known that humans experience a haptic illusion, such as the sensation of being pulled in a particular direction, when asymmetric vibrations are presented. A...
It is known that humans experience a haptic illusion, such as the sensation of being pulled in a particular direction, when asymmetric vibrations are presented. A pulling illusion has been used to provide a force feedback for a virtual reality (VR) system and a pedestrian navigation system, and the asymmetric vibrations can be implemented in any small non-grounded device. However, the design methodology of asymmetric vibration stimuli to induce the pulling illusion has not been fully demonstrated. Although the frequency of the asymmetric vibration is important, findings on the frequency have not been reported. In this study, we clarified the influences of the effects on the pulling illusion based on the investigation of asymmetric vibration frequency differences. Two psychophysical experiments that related to the frequency of asymmetric vibration were performed. Experiment I showed that the illusion occurs for specific vibration waveforms at 40 Hz and 75 Hz. As a result of Experiment II, the threshold was the lowest when the frequency was 40 Hz, and highest when the frequency was 110 Hz. This result supports the previous hypothesis that the Meissner corpuscles and the Ruffini endings contribute to the illusion, while the Pacinian corpuscles do not.
PubMed: 33321954
DOI: 10.3390/s20247086 -
Frontiers in Human Neuroscience 2020In recent years, vibrotactile haptic feedback technology has been widely used for user interfaces in the mobile devices. Although functional neuroimaging studies have...
In recent years, vibrotactile haptic feedback technology has been widely used for user interfaces in the mobile devices. Although functional neuroimaging studies have investigated human brain responses to different types of tactile inputs, the neural mechanisms underlying high-frequency vibrotactile perception are still relatively unknown. Our aim was to investigate neuromagnetic brain responses to high-frequency vibrotactile stimulation, using magnetoencephalography (MEG). We measured 152-channel whole-head MEG in 30 healthy, right-handed volunteers (aged 20-28 years, 15 females). A total of 300 vibrotactile stimuli were presented at the tip of either the left index finger or the right index finger in two separate sessions. Sinusoidal vibrations at 150 Hz for 200 ms were generated with random inter-stimulus intervals between 1.6 and 2.4 s. Both time-locked analysis and time-frequency analysis were performed to identify peak responses and oscillatory modulations elicited by high-frequency vibrations. The significance of the evoked and induced responses for dominant and non-dominant hand stimulation conditions was statistically tested, respectively. The difference in responses between stimulation conditions was also statistically evaluated. Prominent peak responses were observed at 56 ms (M50) and at 100 ms (M100) for both stimulation conditions. The M50 response revealed clear dipolar field patterns in the contralateral side with significant cortical activations in the contralateral primary sensorimotor area, whereas the M100 response was not as prominent as the M50. Vibrotactile stimulation induced significant suppression of both alpha (8-12 Hz) and beta (20-30 Hz) band activity during the mid-latency period (0.2-0.4 s), primarily in sensorimotor areas contralateral to the stimulation side. In addition, a significant alpha enhancement effect in posterior regions was accompanied with alpha suppressions in sensorimotor regions. The alpha suppression was observed in a broader distribution of cortical areas for the non-dominant hand stimulation. Our data demonstrate that high-frequency tactile vibrations, which is known to primarily activate Pacinian corpuscles, elicit somatosensory M50 and M100 responses in the evoked fields and induce modulations of alpha and beta band oscillations during mid-latency periods. Our study is also consistent with that the primary sensorimotor area is significantly involved in the processing of high-frequency vibrotactile information with contralateral dominance.
PubMed: 33250728
DOI: 10.3389/fnhum.2020.576082 -
Purinergic Signalling Mar 2021Purinergic signalling plays important roles in somatosensory and nociceptive transmission in the dorsal horn of the spinal cord under physiological and... (Review)
Review
Purinergic signalling plays important roles in somatosensory and nociceptive transmission in the dorsal horn of the spinal cord under physiological and pathophysiological conditions. Physiologically, ATP mediates excitatory postsynaptic responses in nociceptive transmission in the superficial dorsal horn, and in transmission of innocuous primary afferent inputs in the deep dorsal horn. Additionally, extracellular conversion of ATP to adenosine mediates inhibitory postsynaptic responses from Pacinian corpuscle afferents, and is implicated in analgesia caused by transcutaneous electrical nerve stimulation in humans. In terms of pathological pain, P2X4 receptors de novo expressed on dorsal horn microglia are implicated in pain hypersensitivity following peripheral nerve injury. There is evidence that involvement of such P2X4 receptors is sexually dimorphic, occurring in males but not in females. Thus, the roles of purinergic signalling in physiological and pathological pain processing are complex and remain an ever-expanding field of research.
Topics: Adenosine Triphosphate; Animals; Disease Models, Animal; Humans; Microglia; Neuralgia; Posterior Horn Cells; Receptors, Purinergic; Spinal Cord Dorsal Horn
PubMed: 33169292
DOI: 10.1007/s11302-020-09748-5