Zu den Nervenendigungen (Merkeische Endigungen) in der haarlosen Nasenhaut der Katze

Zusammenfassung Die Nervenendigungen in der Epidermis der haarlosen Haut der Katzennase wurden licht- und elektronenmikroskopisch untersucht. Im Stratum germinativum werden Merkeische Endigungen gefunden. Sie bestehen aus spezialisierten Zellen und je einer anliegenden verdickten Nervenfaser. Diese Rezeptoren werden in zwei Formen beobachtet. Einzelne Zell-Neurit-Komplexe liegen in der Basalschicht der Epidermis über den bindegewebigen Papillen und Gruppen solcher Komplexe im Stratum germinativum der Epidermalleisten (Epithelialzapfen). Die spezialisierten Zellen sind mit den umliegenden Epidermiszellen durch Desmosomen verbunden.Freie Nervenendigungen konnten in der Epidermis der haarlosen Nasenhaut nicht beobachtet werden.

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Nerve endings (Merkel's corpuscles) in hairless skin of the nose of cat

Summary The nerve endings in the epidermis of the hairless skin of the nose of the cat have been studied by means of light and electron microscopy. In the stratum germinativum there are Merkel's corpuscles. They consist of specialized cells with a thickened nerve fibre adjacent to each one of them. These receptors have been observed in two forms. Single cell-neurit-complexes are lying in the basal layer of the epidermis above the connective tissue papillae, and groups of these complexes are situated in the interpapillary pegs of the epidermis. The specialized cells are connected by desmosomes with the neighbouring cells of the epidermis. There are no free nerve endings in the hairless skin of the nose.

     

Innervation of the urinary bladder of Ovis aries L

The authors have extended a preliminary study about the innervation of urinary bladder, confirming the previous results pointing out the presence of metasympathetic ganglions in the wall of urinary bladder. Therefore nine urinary bladders of Ovis aries of different age and both sexes have been studied by Ruffini, Bodian and Bielschowsky's staining methods. It's possible summarize the data on the innervation of urinary bladder in the following way: in the tunica adventitia there are motor and sensitive bundles of myelinated nervous fiber. The formers, after many divisions, penetrate into the tunica muscularis contacting bundles of smooth muscle fibers, while the latters after several divisions after giving rise to thinner bundles, produce Pacini-like and Ruffini-like sense corpuscles and free nervous terminations. Furthermore, some metasympathetic ganglions of different size have been detected throughout the running of the bundles. In the tunica submucosa a diffuse and peculiar non myelinated network is observed, arising from the vegetative nervous fibers.     

Tactile sensation in birds: Physiological insights from avian mechanoreceptors

The sense of touch is ubiquitous in vertebrates and relies upon the detection of mechanical forces in the skin by the tactile end-organs of low-threshold mechanoreceptors. Significant progress has been made in understanding the mechanism of tactile end-organ function using mammalian models, but the detailed mechanics of touch sensation in Meissner and Pacinian corpuscles, the principal detectors of transient touch and vibration, remain obscure. The avian homologs of these corpuscles present an opportunity for functional study of mechanosensation in these structures, due to their relative accessibility and high abundance in the bill skin of tactile-foraging waterfowl. Here, we review the current knowledge of mechanosensory end-organs in birds and highlight the utility of the avian model to understand general principles of touch detection in the glabrous skin of vertebrates.     

Mesenteric and tactile Pacinian corpuscles are anatomically and physiologically comparable

Pacinian corpuscles (PCs) in cat mesentery have been studied extensively to help determine the structural and functional bases of tactile mechanotransduction. Although we, like many other investigators, have found that the mesenteric receptors are anatomically very similar to those found in mammalian skin, few physiological characteristics of the mesenteric PCs and those of the skin have been compared. Action-potential rate-amplitude and frequency characteristics (10 Hz-1 KHz), as well as interval (IH) and peri-stimulus-time (PSTH) histograms in response to sinusoidal displacements were obtained from nerve fibers innervating mesenteric PCs and from PC fibers innervating cat glabrous skin. The intensity characteristics obtained on both preparations showed similar response profiles, including equal slopes for low stimulus intensities (approximately 10, with impulse ratios/20 dB displacement) and one and two impulse/cycle entrainment. The frequency characteristics of both groups were U-shaped with similar low-frequency slopes (-12.5 dB/octave) and bandwidths (Q(3dB) = 1.4). The best frequency for both the tactile PCs' and mesenteric PCs was 250 Hz, which is in the expected range. The IHs showed entrainment and the PSTHs showed neither transient responses nor adaptation to steady-state sinusoidal stimuli. The functional similarity between mesenteric PCs' nerve responses and those of tactile PC afferents, as well as the receptors' anatomical similarity, lead us to suggest that the mesenteric PC can act as a model for those in the skin. Furthermore, since the frequency characteristics of the two PC types are similar, it is concluded that the skin, while attenuating stimulus intensity, does not impart temporal filtering of vibratory stimuli.     

Mesenteric and tactile Pacinian corpuscles are anatomically and physiologically comparable

Pacinian corpuscles (PCs) in cat mesentery have been studied extensively to help determine the structural and functional bases of tactile mechanotransduction. Although we, like many other investigators, have found that the mesenteric receptors are anatomically very similar to those found in mammalian skin, few physiological characteristics of the mesenteric PCs and those of the skin have been compared. Action-potential rate-amplitude and frequency characteristics (10 Hz–1 KHz), as well as interval (IH) and peri-stimulus-time (PSTH) histograms in response to sinusoidal displacements were obtained from nerve fibers innervating mesenteric PCs and from PC fibers innervating cat glabrous skin. The intensity characteristics obtained on both preparations showed similar response profiles, including equal slopes for low stimulus intensities (approximately 10, with impulse ratios/20 dB displacement) and one and two impulse/cycle entrainment. The frequency characteristics of both groups were U-shaped with similar low-frequency slopes (?12.5 dB/octave) and bandwidths (Q_3dB = 1.4). The best frequency for both the tactile PCs' and mesenteric PCs was 250 Hz, which is in the expected range. The IHs showed entrainment and the PSTHs showed neither transient responses nor adaptation to steady-state sinusoidal stimuli. The functional similarity between mesenteric PCs' nerve responses and those of tactile PC afferents, as well as the receptors’ anatomical similarity, lead us to suggest that the mesenteric PC can act as a model for those in the skin. Furthermore, since the frequency characteristics of the two PC types are similar, it is concluded that the skin, while attenuating stimulus intensity, does not impart temporal filtering of vibratory stimuli.     

Innervation of periodontal ligament and dental pulp in the rat incisor: An immunohistochemical investigation of neurofilament protein and glia-specific S-100 protein

Summary Nervous elements in the periodontal ligament and dental pulp of rat incisors were investigated by means of immunohistochemistry for neurofilament protein (NFP) and glia-specific S-100 protein. The periodontal ligament in the incisors was densely innervated by NFP-immunoreactive nerve fibers; the distribution of the nerve fibers and their terminations differed markedly from those in molars. NFP-positive, thick nerve bundles entered the lingual periodontal ligament through slits located in the mid-region of the alveolar socket, and immediately formed numerous Ruffini-like corpuscles. In the labial periodontal ligament, all of the NFP-immunoreactive nerve fibers terminated in free endings. The restricted location of the stretch receptor, Ruffini-like corpuscle, in the lingual periodontal ligament appears to be an essential element, because this region is regularly extended during mastication. The nervous elements were restricted to the alveolar half of the periodontal ligament in every region; they avoided the dental half of the periodontal ligament, which presumably moves continuously with the tooth. Pulpal nerve fibers in incisors also showed a characteristic distribution different from those in molars; individual nerve fibers with beaded structures ran in the center of the pulp toward the incisai edge, and did not form the subodontoblastic nerve plexus of Raschkow.Immunostaining for S-100 protein revealed a distribution pattern of nervous elements similar to that for NFP, suggesting that the nerves supplying the periodontal ligament and dental pulp were mostly covered by a Schwann sheath.     

Immunohistochemistry of Grandry corpuscles in the oral mucosa of the duck bill: a light- and electron-microscopic study

Grandry corpuscles in the oral mucosa of the upper bill of the duck were immunohistochemically studied using antisera against calcitonin gene-related peptide (CGRP), galanin, methionine-enkephalin, neuropeptide Y (NPY), somatostatin, substance P (SP) and vasoactive intestinal peptide (VIP). Grandry corpuscles in the lamina propria selectively showed only SP-like immunoreactivity. Herbst corpuscles distributed near Grandry corpuscles were negative to all antisera applied. Although immunoreactive products in the Grandry corpuscles were found as granules in the peripheral cytoplasm of the Grandry cell, the axon terminals and satellite cells exhibited no reactivity. In pre-embedding electron-microscopic sections, SP-like immunoreactive products visualized with 3,3-diaminobezidine were localized in the granules of Grandry cells, but no labeling was observed in the cytoplasmic matrix or cell organelles. Electron-immunocytochemical labeling with colloidal gold by the post-embedding method clearly demonstrated that the SP antigen was localized only in the granules. It is presumed that Grandry cells have a secretory function. However, the function and the method of release of the SP contained in the observed granules remains obscure. Some CGRP-, NPY-, SP- and VIP-like-immunoreactive nerve fibers with varicosities associated with blood vessels and nerve fiber bundles of various sizes were observed in the lamina propria, but no such fibers penetrated into the intraepitherial layer. Nerve fibers positive for SP and VIP were also found in the interlobular connective tissue of the palatine glands. Some SP-positive neurons were detected in the vicinity of the palatine glands.     

Plexiform vascular structures in the human digital dermal layer: a SEM--corrosion casting morphological study

This study aimed to describe the impressive diversity of vascular plexiform structures of the hypodermal layer of human skin. We chose the human body site with the highest concentration of dermal corpuscles, the human digit, and processed it with the corrosion casting technique and scanning electron microscopy analysis (SEM). This approach proved to be the best tool to study these microvascular architectures, free from any interference by surrounding tissues. We took high-definition pictures of the vascular network of sweat glands, thermoreceptorial and tactile corpuscles, the vessels constituting the glomic bodies and those feeding the hair follicles. We observed that the three-dimensional disposition of these vessels strictly depends on the shape of the corpuscles supplied. We could see the tubular vascularization of the excretory duct of sweat glands and the ovoid one feeding their bodies, sometimes made up of two lobes. In some cases, knowledge of these morphological data regarding the normal disposition in space and intrinsic vascularization structure of the dermal corpuscles can help to explain many of the physiopathological changes occurring during chronic microangiopathic diseases.     

Innervation der unbehaarten Nasenhaut des Maulwurfs (Talpa europaea)

Zusammenfassung Die Epidermis der unbehaarten Nasenhaut des Maulwurfs bildet regelmäßig angeordnete, einzeln stehende Papillen, die sich über die Epitheloberfläche erheben. Jede dieser Papillen entspricht einem Epithelzapfen, der sich pufferförmig verdickend in das Corium einsenkt. Diese epidermale Einheit wird als Eimersches Organ bezeichnet.Die Eimerschen Organe werden von 2 Typen von Nervenendigungen versorgt, von Merkelschen Endigungen und von freien Nervenfasern. Die Merkelschen Endigungen sind in das Stratum basale der Epidermis eingelagert und bestehen aus Merkelschen Zellen und kelchförmig verdickten Nervenfasern, die den basalen Teil der Zellen umfassen. Die zuführenden Nervenfasern sind myelinisiert, solange sie im dermalen Nervenplexus verlaufen. Jeder Epithelzapfen enthält 3–5 Merkelsche Endigungen. Die freien Nervenfasern treten in 2 Typen auf. In der Mitte jedes Epithelzapfens läuft eine etwas stärkere Nervenfaser, ca. 2,5 stark. Zirkulär umgeben sie ungefähr 20 schwächere Nervenfasern, 1–1,5 stark, die senkrecht gegen die Epitheloberfläche ziehen und mit einer knopfartigen Erweiterung im Stratum granulosum enden. Beide Fasertypen werden vom Eintritt in die Epidermis an in Epidermiszellen invaginiert. Infolgedessen umhüllen die Zellen der Epidermis die Nervenfaser ähnlich wie Schwannsche Zellen. Mit dem Interzellularraum ist das Axon mit einer dem Mesaxon ähnlichen Spalte verbunden. In der Peripherie der Epidermispapillen sind vereinzelte Nervenfasern in gleicher Weise angeordnet.

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Innervation of hairless skin of the nose of moleI. Intraepidermal nerve endings

Summary The epidermis of the hairless skin of the mole's nose forms regularly arranged separate papillae which protrude above the surface of the epithelium. An individual epithelial peg which penetrates with a buffer-shaped thickening into the corium conforms to each papilla. This epidermal unit is called Eimer's organ.These Eimer's organs are provided with two types of nerve terminals: Merkel's corpuscles and free nerve endings. The Merkel's corpuscles are embedded in the stratum basale of the epidermis and consist of cells and nerve fibres which encircle the basal part of the cells. The afferent (dendritic) nerve fibres are myelinated as long as run in the dermal nerve plexus. Every epidermal peg contains 3 to 5 Merkel's corpuscles.In addition to nerve fibres connected to corpuscles, there are two types of free nerve endings. A thick nerve fibre, about 2.5 in diameter, runs in the centre of each epidermal peg. About 20 thin nerve fibres, 1 to 1.5 in diameter, encircle the thick central axon, running perpendicularly to the epidermal surface. Both types of nerve fibres end with knob-like thickening in the stratum granulosum. When entering the epidermis both types of nerve fibres become invaginated into cytoplasm of the epidermal cells. Thus the nerve fibres are ensheathed by the cells of the epidermis in the same manner as by Schwann's cells. The axon has access to the intercellular space by a gap resembling the situation in mesaxons. Sporadic nerve fibres occur in the periphery of the epidermal papillae which are aranged in the same pattern.

Für die sprachlichen Verbesserungen möchte ich mich besonders bei Herrn Prof. Dr. Dr. H.-R. Duncker bedanken.     

Innervation of the incisors and periodontal ligament in several rodents: an immunohistochemical study of neurofilament protein and glia-specific S-100 protein

The present immunohistochemical study by use of antisera against neurofilament protein (NFP) and S-100 protein dealt with the innervation of the upper incisors and periodontal ligament in five species of rodents including the guinea pig, hamster, Mongolian gerbil (Meriones unguicularis), mouse and squirrel (Tamias sibiricus). The innervation pattern of the periodontal ligament and dental pulp in the incisors of five rodents was fundamentally identical to that in the rat, which we have previously demonstrated by the same method. The NFP-positive Ruffini-like corpuscles were concentrated in the middle region of the lingual periodontal ligament in all the species examined, suggesting that this particular arrangement of Ruffini-like corpuscles, possibly stretch receptors, was essential to the rodent incisor. The labial periodontal ligament, on the other hand, contained less numerous NFP-positive nerves, these terminating among collagen fibers as free endings. The gerbil and squirrel in particular possessed only a few nerve fibers in the labial periodontal ligament. It was thus presumed that the labial periodontal ligament might be less significant as a mechanoreceptive site than the lingual periodontal ligament. The NFP-positive pulpal nerves, beaded or smooth in shape, ran parallel to the tooth axis, but never extended to the odontoblastic layer; no subodontoblastic plexus was found in the incisors of any of the rodents. S-100-immunopositive nervous elements were distributed in the periodontal ligament and dental pulp of all the rodent species examined, showing a distribution pattern similar to the NFP-positive nerves. Only in the squirrel did odontoblasts show an intense S-100 immunoreactivity.     

Study of individual Pacinian corpuscle mechanoreceptors following application of colchicine to a nerve]

Colchicine application to the cat caudal mesenteric nerve containing sensory fibers for single mechanoreceptors (Pacinian corpuscles) causes degeneration of the axis cast of the nerve endings. Ultrastructural changes in the receptors showed no difference from the axonal degeneration after the nerve section but the rate of degeneration was considerably slower. Ultrastructural, electrophysiological, and biochemical changes occurring in the Pacinian corpuscles were not the result of direct action of colchicine, but appeared to be realized through the nerve by the axoplasmic transport block. It is suggested that the receptor's structure is under the sensory neuron neurotrophic control.     

Development of the corpuscles of Stannius in the anabantid teleost, Colisa lalia

The development of Stannius corpuscles in the teleost Colisa lalia is described. Certain cells of the mesonephric tubules differentiate and proliferate to form buds which evaginate and finally become separated from the structure of origin. The separated cellular masses undergo further histologic differentiation to attain the adult structures. The corpuscles in C. laha, in contrast to some other teleosts, develop only from mesonephric tubules. A possible explanation for the different types of distribution of Stannius corpuscles in teleosts is suggested, and the possible homology of these structures with part of the adrenal cortex or higher vertebrates is discussed.     

Distribution of the 75-kD Low-Affinity Nerve Growth Factor Receptor in the Primate Peripheral Nervous System

Disruption of the 75-kD low-affinity nerve growth factor (NGF) receptor (p75) has been shown to result in sensory and sympathetic nervous system deficits (Lee et al., 1992a,b). In order to establish precisely which subsets of neurons are capable of responding to neurotrophins (NTs) through the low-affinity NGF receptor, p75 was localized in the primate autonomic and somatic sensory nervous systems. In the autonomic system, cell bodies of some parasympathetic and enteric neurons expressed detectable levels of p75, whereas all sympathetic neurons expressed the protein. In the sensory system, some, but not all, cell bodies were labeled in cranial and spinal sensory ganglia and in the mesencephalic nucleus. Some peripheral and central projections of the sensory neurons were also labeled. Centrally, most of the labeled processes were found in regions containing primarily small unmyelinated fibers, including lamina II of Rexed and areas of the solitary tract and nucleus. Peripherally, labeled processes were associated with unmyelinated nerves and specialized structures such as taste buds and Meissner corpuscles, but not with myelinated processes. This study indicates that the subset of neurons in the autonomic nervous system likely to be capable of responding to neurotrophins is broader than generally thought, and that p75-ex-pressing neurons tend to be clustered. Moreover, in the sensory nervous system p75 is expressed by most cell bodies, but expression in their projections is restricted both peripherally and centrally to unmyelinated processes and nerve terminals.     

Occurrence of substance P-like immunoreactive nerve fibers in Krause corpuscles of the dog's tongue

Substance P-like immunoreactive (SPLI) nerve fibers were demonstrated in the Krause corpuscles of the dog's tongue using the indirect immunofluorescence method and cholinesterase histochemistry. SPLI nerve fibers were often in contact with Krause end bulbs and occasionally entered them. From this result it was suggested that substance P might be involved in sensory mechanism of the Krause apparatus.     

Functional characteristics of the skin receptor structures in animals and man

Threshold electrical reactions of single fibers from the ischiadic nerve of rats to mechanical stimulation and rectangle impulses of focused ultrasound have been compared with respect to the parameters of stimulation to the effect of focused ultrasound on the skin of human fingers evoking different sensations. It was concluded that low-threshold fibers may be associated with tactile reception, mean-threshold ones--with tactile and thermal, whereas high-threshold fibers may be referred to reception of specific skin pain.     

Effects of fusion between tactile and proprioceptive inputs on tactile perception

Tactile perception is typically considered the result of cortical interpretation of afferent signals from a network of mechanical sensors underneath the skin. Yet, tactile illusion studies suggest that tactile perception can be elicited without afferent signals from mechanoceptors. Therefore, the extent that tactile perception arises from isomorphic mapping of tactile afferents onto the somatosensory cortex remains controversial. We tested whether isomorphic mapping of tactile afferent fibers onto the cortex leads directly to tactile perception by examining whether it is independent from proprioceptive input by evaluating the impact of different hand postures on the perception of a tactile illusion across fingertips. Using the Cutaneous Rabbit Effect, a well studied illusion evoking the perception that a stimulus occurs at a location where none has been delivered, we found that hand posture has a significant effect on the perception of the illusion across the fingertips. This finding emphasizes that tactile perception arises from integration of perceived mechanical and proprioceptive input and not purely from tactile interaction with the external environment.     

Distribution of neurofilament-immunoreactive nerve fibers in human skin

Neurofilament immunoreactive nerve fibers were demonstrated in human skin using indirect immunohistochemical technique with antibodies to neurofilament polypeptides. Neurofilament-positive fibers were seen as free nerve endings in the epidermis and in dermal papilla, in Meissner's corpuscles and as fibers crossing in the dermis. Strongly fluorescent nerve fibers were also seen around hair follicles, sweat gland ducts and sometimes in relation to blood vessels. From the distribution pattern it was concluded that predominantly sensory nerve fibers were labelled and that this technique may be used to study reinnervation of cutaneous sensory nerves following traumatic injuries and surgical procedures.     

The neural basis of tactile texture perception

Running our fingers across a textured surface gives rise to two types of skin deformations, each transduced by different tactile nerve fibers. Coarse features produce large-scale skin deformations whose spatial configuration is reflected in the spatial pattern of activation of some tactile fibers. Scanning a finely textured surface elicits vibrations in the skin, which in turn evoked temporally patterned responses in other fibers. These two neural codes—spatial and temporal—drive a spectrum of neural response properties in somatosensory cortex: At one extreme, neurons are sensitive to spatial patterns and encode coarse features; at the other extreme, neurons are sensitive to vibrations and encode fine features. While the texture responses of nerve fibers are dependent on scanning speed, those of cortical neurons are less so, giving rise to a speed invariant texture percept. Neurons in high-level somatosensory cortices combine information about texture with information about task variables.     

Distribution of sensory receptors in the flexor carpi radialis muscle of the cat

The structures and distribution of encapsulated muscle receptors were examined in serial transverse sections of flexor carpi radialis in the adult cat. Four types of receptors (muscle spindles, Golgi tendon organs, paciniform, and Pacinian corpuscles) were identified. Their structures resembled those encountered in other limb muscles. Pacinian corpuscles were rare and occurred only in the external fascial coat of the muscle near its origin. The other three receptor types were distributed in an uneven but consistent pattern throughout the muscle. As noted previously (Gonyea and Ericson, '77), spindles were largely confined to a deep muscle region comprising less than 20% of the muscle volume, located directly between the long tendon of origin and the tendon of insertion. This region contains the largest proportion of type SO muscle fibers (Gonyea and Ericson, '77). Tendon organs and paciniform corpuscles were concentrated along the tendons that lined the spindle-rich muscle region. This region appeared to be composed of extrafusal fibers that were shorter and of more oblique pinnation than those in other regions. The localization of muscle receptors to the "oxidative" core of the muscle in its direct line of pull may have functional implications for afferent input to the spinal cord which are discussed. In addition, the possibility is raised that there are more paciniform corpuscles in flexor carpi radialis (and possibly other muscles) than previously thought.     

Characteristics of development of the rat embryonal lung after resection of the maternal lung

Histological and electron microscopic studies of embryos from pulmonectomized female rats have revealed retarded differentiation of respiratory rudiment epithelium manifested in delayed appearance of osmiophylic laminar corpuscles and decreased number of type II pneumocytes in respiratory rudiment lining. Osmiophylic laminar corpuscles in them were less differentiated, as compared to the control. In addition, embryonic lungs in pulmonectomized rats were characterized by excessive mesenchyma development and respective decrease in respiratory rudiment area. It is concluded that embryonic lungs developed during pulmonary tissue deficit in the mother are functionally less mature.