The terminal Schwann cells that represent glial elements in cutaneous mechanoreceptors are characterized by their processes that branch into lamellar coverings of different axon terminals. By experiments with isolated lanceolate endings―motion detectors of rat vibrissae―we have previously shown these cells to respond to application of the intercellular signal substance ATP with an elevation of the cytoplasmic Ca2+ concentration through activation of their purinceptors P2Y2. This report presents our recent confocal image analyses demonstrating that the Schwann lamellae can detect ATP release induced by local mechanical stimuli with their own purinoceptors to generate a Ca signal confined within the length of the processes (1), and that endogenous ecto-ATPase regulates the range of intracellular signal propagation (2), and that caveola-dependent localization of Ca signaling molecules to the Schwann lamellae is essential for the subcellular compartmentalization in the purinergic cell signals. Possible Schwann cell effects induced by the compartmentalized signals on the accompanying mechanoreceptor axons in the intact organ will be discussed.
Most of living things on the earth survive by detecting ambient temperatures and adapting their changes. Among the molecules involved in the ambient temperature detection, thermosensitive transient receptor potential (TRP) channels are conserved from insects to mammals. Nine thermosensitive TRP channels are known in mammals and they detect wide-range of temperature changes from cold to hot. Temperatures above 43℃ and below 15℃ are believed to cause pain in our body, and accordingly some of the thermosensitive can be viewed as nociceptive receptors. How temperature opens the TRP channels still remain unknown. Crystal structures of the thermosensitive TRP channels are not clarified, and single particle analysis data with cryoEM were reported in some channels.
The periodontal ligament serving as tooth support or anchor has a rich sensory nerve supply to function as sensory input apparatus to mastication system. The periodontal ligament contains nociceptive free nerve endings and mechanoreceptors. Stimuli applied to teeth easily evoke various oral reflexes, which make smooth mastication possible via the periodontal mechanoreceptors. Morphological and physiological studies have revealed that Ruffini ending, categorized as low-threshold slowly adapting type II, is a primarily mechanoreceptor in the periodontal ligament. The periodontal Ruffini endings are characterized by expanded axon terminals with extensive ramifications and by an association with the terminal or lamellar Schwann cells. Their axon terminals expressed various kinds of proteins such as Ca-binding protein. The mechanical stimuli due to tooth eruption and occlusion might be a prerequisite for the final differentiation and maturation of the periodontal Ruffini endings. Many experimental studies have revealed that periodontal Ruffini endings have high potential for neuroplasticity. It appears that the development/regeneration/maturation of the periodontal Ruffini endings is controlled by multiple neurotrophins including BDNF, NT-4/5 and GDNF in a stage-specific manner.
Itch is an essential symptom of atopic dermatitis (AD) and constitutes one of the major diagnostic criteria of AD. Compared with healthy individuals, the skin of atopic patients is characterized by specific features that result in a lower itch threshold and hypersensitivity to certain non-specific triggers. Thus, itch in AD has a chronic and refractory character and can sometimes be very resistant to treatment. The itch-scratch vicious circle is frequently observed in patients with AD, being an important factor in the maintenance of AD symptoms. Here, we focus on the role of skin as a sensory receptor and overview the regulation of itch shown in AD.
Three-dimensional cytoarchitecture of blood vessels from aorta to vein via microvasculature were revealed by scanning electron microscopy after connective tissue components were removed. The blood vessel of the mammary gland was continuously observed from an arteriole to a venule. Spindle-shaped smooth muscle cells (SMCs) and branched- SMCs, and elongated- pericytes and spidery-pericytes were found on the endothelial tube in accord with the description of microvasculature reported by Rhodin. In the intermediate segment of the arteriovenous anastomoses, the SMCs of the outer layer were irregularly spindle-shaped and circularly arranged, while the epithelioid cells of the inner layer were polygonal in shape and irregularly oriented. In the mesenteric artery, the SMCs were sickle-like and almost circularly oriented. Those of the thoracic aorta were closely apposed to form muscle bundles, forming a lattice-like structure in the outermost lamella, and arranged parallel to form muscle sheets in the inner lamellae. The SMCs in the mesenteric vein were circumferentially flattened, and along with the SMCs in the coronary artery, were irregular in shape and arrangement. The asteroid SMCs were observed in the subarachnoidal arteriole. Even denuded vessels were observed in some transgenic mice. These results suggested the usefulness of scanning electron microscopy in vascular research.
High-resolution electron microscopy is entering a new era with the development of aberration correction electron optics. Thanks to the steady efforts of researchers over a period of 50 years, this development enables us to directly observe individual light atoms such as carbon and oxygen as well as single molecules and impurities in bulk solids. High-resolution electron microscopes are now indispensable tools to facilitate nanotechnology studies in many fields. In the present review, a brief history of the development of aberration correction is outlined, and some future directions using the technique are summarized including a discussion on phase plates.
Procedure of obtaining serial ultrathin sections for electron microscopy consists of several steps: cutting of uniform very thin sections by ultramicrotome; making ribbon sections for taking pictures in electron microscope one after another; separating ribbon sections to fixed length for mounting grids; and collecting ribbons on the grids with no failure. The present report describes a reliable method for obtaining serial ultrathin sections from a resin block of biological tissues using new small tools.
TEM diffraction contrast technique is considerably useful for observation of microstructures in comparatively thick specimens to which high-resolution TEM/STEM is not applicable and grasp of the features of specimens over wide area. In this article, mechanism of the diffraction-contrast imaging of lattice defects and its applications are concisely presented.
In order to analyze high active materials such as lithium ion battery’s electrodes, an air protection system was developed consisting of air protection specimen holders, a glove box, a focused ion beam system and an electron microscope. The effectiveness was tested using negative electrode of lithium ion battery after charged. As a result, it is possible to transport, fabricate and observe it without specimen transformation. The distribution of lithium was clearly identified.
Investigation of the atomic structure in solid is essential for materials science. In order to analyze the local structures around the specific atoms by reconstructing a three dimensional (3D) atomic images under laboratory experiments, we propose a new method, which is termed “internal-detector electron holography”. The intensity variation of the characteristic X-ray as a function of direction of the incident electron beam forms an atomic resolution hologram around atoms emitting characteristic X-rays. We demonstrated the internal detector electron holography of a SrTiO3 single crystal using a scanning electron microscope and Ge solid state detector. A 3D atomic image of SrTiO3 was successfully visualized by a fitting-based reconstruction algorithm. The atoms of all of the elements are clearly seen at the theoretical coordinates without artifacts. This method has a great potential of various applications for materials and surface sciences.
FIB/SEM (DualBeamTM) is well known system as one of the best system for failure analysis in material science field. Ion-beam serial milling and reconstruction is a 3D reconstruction technique using a combination of DB and computed tomography technique. The technique is an important application of DB in material science field. Now it becomes popular in life science field gradually. Then we introduce its technique and application for life science field.