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Survival of Pacinian corpuscles after denervation in adult rats.

The ultrastructure of Pacinian corpuscles located on the crural interosseous membrane was studied in adult rats 6h to 10 months after transection of the right sciatic nerve. Axon terminals degenerated one day after transection and were engulfed and resorbed by cells of the inner core within one week. The axial space left after removal of the axonal debris was closed by the lamellae of the inner core. The main structural features of the inner core and capsule remained preserved after denervation throughout the period of study. The denervated inner cores, however, became atrophic 10 months after neurotomy, their mean diameter being reduced by 17.5% compared with that of contralateral control corpuscles. The number of capsular lamellae was unaltered, and perineurial pathways of the peripheral nerve stump remained preserved. Schwann cells proliferated and formed Büngner bands during the first month after denervation, but retracted their processes and became atrophic at later stages after neurotomy. Survival of Pacinian corpuscles after long-term denervation in adult rats is in contrast to their rapid degeneration within several days after nerve section in neonates.

Animals↗

The electron microscopic localization of alkaline phosphatase in Pacinian corpuscles of the cat.

The ultrastructural localization of alkaline phosphatase has been studied in Pacinian corpuscles of the cat mesentery by the method of Mayahara et al. (1967) with 3 substrates. As control studies, specimens were incubated in the medium containing L-cysteine (10 mmol) or EDTA (5 mmol). The electron opaque final reaction product was observed on plasmic membranes and in cytoplasm and pinocytotic vesicles of the inner core cells. The precipitate was present also in rough endoplasmic reticulum, multivesicular bodies, and cytoplasmic vacuoles of the inner core lamellae. The axon revealed the positive enzymatic activity in the axolemma and the scattered precipitate was found in axoplasm. The pinocytotic vesicles in the capillary endothelium entering Pacinian corpuscles contained the reaction product, too. The capsule lamellae were devoid of precipitate. Localization of alkaline phosphatase in pinocytotic vesicles of the inner core lamellae and capillary wall support the opinion that this enzyme plays the significant role in the phenomenon of the transport of molecules through inner core lamellae from capillaries to the axon in Pacinian corpuscles.

Alkaline Phosphatase↗

Slow-adapting responses of the Pacinian corpuscles of cat planta.

Slow-adapting impulses were recorded from the single nerve fiber innervating the Pacinian corpuscle of the cat planta, which was stimulated by constant pressure. Slow-adapting Pacinian corpuscles responded to both low-frequency (0.1-0.01 Hz) and high-frequency (400-800 Hz) vibrations. Simultaneously performed electron microscopy showed that there were no definite ultrastructural differences between slow- and fast-adapting Pacinian corpuscles.

Adaptation, Physiological↗

The enigma of sensitivity in Pacinian corpuscles: a critical review and hypothesis of mechano-electric transduction.

The present report reviews the physiological and morphological specializations of Pacinian corpuscles and other mechanoreceptors that are present in the skin and connective tissues of the body as well as the cochlea. The remarkable sensitivity of Pacinian corpuscles is such that the only form of mechanical energy that could be perceived by a Pacinian corpuscle is a sound wave. In fact the human finger as demonstrated by Munger and Ide (1987) can perceive sound waves when water is the coupling agent. The structural specializations are equally remarkable with extensive membrane specializations of both the inner core and inner portion of the outer core. The halves of the inner core are each coupled with gap junctions and the inner portion of the outer core joined with numerous tight junctions. The cleft regions have specializations involving the axolemma that consist of numerous axonal spines containing bundles of filaments projecting into the cleft of the inner core. These structural specializations are thought to represent specializations for mechano-electric transduction analogous in many respects to the hair cells of the cochlea. A hypothesis for mechano-electric transduction is presented that may account in part for the extreme sensitivity of Pacinian corpuscles and other mechanoreceptors.

Animals↗

Reinnervation of Pacinian corpuscles by CNS axons after transplantation to the dorsal column: incidence and ultrastructure.

We have investigated the capacity of injured axons in the spinal dorsal columns of young adult rats to reinnervate grafted Pacinian corpuscles. A branch of the hindlimb interosseous nerve with a group of crural Pacinian corpuscles attached to it was autotransplanted to the surface of the spinal cord and the nerve stump was implanted into the dorsal column. Two to three months later 16 grafts were removed for examination by light and electron microscopy. By 3 months after transplantation almost all Schwann cell columns of the grafted nerve branch were occupied by regenerated myelinated and unmyelinated axons. Of 41 corpuscles examined by electron microscopy 24 were reinnervated by 1-3 myelinated fibres which gave rise to multiple terminals in the inner core. The remaining corpuscles appeared to be denervated. Only two of the reinnervated corpuscles contained regenerated endings which reiterated the distinct ultrastructure of normal presynaptic terminals of CNS axons, characterized by clusters of lucent vesicles and paramembranous densities. All other corpuscles were reinnervated by terminals which resembled peripheral mechanosensory endings as they contained mitochondria and very few vesicles. One such corpuscle was coinnervated by small terminals filled with large dense cored vesicles. We assume that the majority of grafted Pacinian corpuscles have been reinnervated by dorsal column axons and that the regenerated terminals with the ultrastructure of peripheral mechanosensory endings derive from central axons of primary sensory neurons, which are apparently capable of constructing mechanosensory-like terminals in response to signals from the Pacinian corpuscles. The vesicle-filled endings are probably formed by second order sensory neurons, corticospinal neurons and small peptidergic neurons unable to adjust their terminals to the new target.

Animals↗

Pacinian corpuscle in the human pancreas.

During our systematic examination of the distribution of cytochrome P450 enzymes in the normal and diseased human pancreas, we observed a Pacinian corpuscle in a serial section of a tissue from a pancreatic cancer patient. We report the histologic and immunohistochemical patterns in this corpuscle and review the literature. The Pacinian corpuscle was situated within the pancreas of a 76-year-old woman with cancer in the head of the pancreas. We could demonstrate immunoreactivity within the corpuscle for the neurofilament protein. neuron-specific enolase, S-100 Protein, and for four cytochrome P450-isozymes. The possible function of Pacinian corpuscles in the mammalian and human pancreas is discussed.

Aged↗

K and Na ion content in the Pacinian corpuscle fluid and its role in the activity of receptors.

1. Potassium and sodium concentrations within the Pacinian corpuscle fluid have been investigated in adult cats. The sodium and potassium contents of samples were estimated by means of integrative ultramicroflame photometry. 2. The analytical results showed the values of the potassium concentration in the Pacinian corpuscle fluid and in the blood plasma to be 6.19 +/- 0.72 and 2.78 +/- 0.38 mequiv/1, respectively. 3. The increasing excitability of the Pacinian corpuscle in potassium-rich solution was shown by electrophysiologic methods. In potassium-free solution two phases of changing receptor excitability were observed. 4. Removal of sodium from external solution reduced the receptor potential to 10% of its original value. 5. Some mechanisms of the increase in excitability of primary tissue mechanoreceptors and secondary mechanoreceptors of the sense organs are discussed.

Animals↗

A re-evaluation of the cytology of cat Pacinian corpuscles II. The extreme tip of the axon.

The present report is the second of two studies re-evaluating the cytological characteristics of Pacinian corpuscles. The extreme tip of the axon of a Pacinian corpuscle has been identified and is quite different from the previously described ultraterminal region. The latter is the site where the inner core lamellae begin to terminate and is characterized by a smooth axolemma. The extreme tip lacks inner core lamellae directly abutting the axolemma and is instead characterized by the presence of many axonal spines projecting into a matrix of basal lamina-like material. The extreme tip of the axon thus resembles the organization of the axolemma facing the clefts of the inner core. The axonal spines at the cleft and extreme tip are proposed as a site of restricted current flow due to the tight apposition of inner core lamellae to the axolemma of X-axis. The hemi-inner cores thus could restrict current flow to the cleft. These anatomical specializations could represent both a source and a sink for K+ ions during mechano-electric transduction and account in part for the exquisite sensitivity of Pacinian corpuscles to complex pressure waves.

Animals↗

The form and distribution of the receptive fields of Pacinian corpuscles found in and around the cat's large foot pad.

1. Firing thresholds of Pacinian corpuscles situated within or close to the large pad of the cat's hind foot have been determined following step displacements applied to various points on the pad surface.2. The most sensitive positions on the receptive fields of thirty-one corpuscles were distributed unevenly over the pad. About half were situated close to the interlobular crease lines, and most of the others were at the edge of the pad.3. Threshold receptive fields were usually of complex form, with more than one region of low threshold.4. The approximate locations of a number of Pacinian corpuscles whose fields had been mapped were determined by dissection.5. The most sensitive position on the pad was usually at the closest point to the corpuscle. If the corpuscle was situated outside the pad itself, it was therefore usually most easily excited from some point at the edge of the pad. However, a minority of Pacinian corpuscles were most easily stimulated from some region other than that closest to them.6. It is suggested that previous estimates of the ability of this population of receptors to transmit information about the positions of stimuli (Gray, 1966) must be re-evaluated in the light of the non-uniform distribution and asymmetry of their cutaneous receptive fields.

Action Potentials↗

Subepineural pacinian corpuscle: a cause of digital pain.

A patient is presented who had chronic digital pain as a result of an abnormally located subepineural pacinian corpuscle. The patient had complete relief of her symptoms and return of normal digital function following removal of the pacinian corpuscle. A review of the literature concerning this entity revealed very few reported cases. However, these cases shared many of the same symptoms, as well as both physical and operative findings. It is suggested that patients suffering from digital pain of unknown etiology with a previous history of direct or indirect trauma may benefit from a localized operative exploration of the digit to remove an abnormally located pacinian corpuscle affecting the digital nerve.

Adolescent↗

Lectin and proteoglycan histochemistry of feline pacinian corpuscles.

We studied carbohydrate residues of glycoproteins and proteoglycans (PGs) in peritoneal Pacinian corpuscles of five adult cats. Terminal monosaccharides of glycoproteins and related polysaccharides were identified by lectin histochemistry and the PGs and glycosaminoglycans (GAGs) by specific antibodies. The most intensive lectin staining reactions indicated an abundance of glycoconjugates with terminal mannose (Man) or sialic acid residues, but no complex-type oligosaccharides were detected within the corpuscles. Terminal fucose (Fuc) and galactose (Gal) residues typical for O-linked mucin-type glycoproteins generally associated with high water binding capacity were also absent. Antibodies against unsulfated chondroitin (C-0-S), chondroitin-4-sulfate (C-4-S), and decorin showed positive reactions in the interfibrillar spaces between the lamellae, around collagen fibers, and around the lamellae of the perineural capsule, especially in the outer parts known to contain Type II collagen. Biglycan showed a preference for the innermost part of the perineural capsule (intermediate layer), known to contain Type V collagen. Collagen V and biglycan are both linked to growth processes. Hyaluronic acid (HA), chondroitin-6-sulfate (C-6-S) chains, and a chondroitin sulfate proteoglycan (CSPG) were co-localized in the terminal glia. The study of carbohydrates with high water binding capacity may contribute to our understanding of the high viscoelasticity of Pacinian corpuscles.

Animals↗

Changes in primate Pacinian corpuscles following volar pad excision and skin grafting. A preliminary report.

Human fingertip avulsion injuries were simulated by excising volar digital pads in stump-tailed monkeys. Half the defects were covered with split-skin grafts from the forearm, and half with full-thickness grafts of fingertip skin. Innervated pacinian corpuscles were found in the center of these grafts 3 months after the operation. The site of origin of these corpuscles is undefined. Denervation and devascularization of pacinian corpuscles resulted in alterations of their gross architecture, size, and innervation. The possibility exists that these alterations result from a dynamic adaptation of pacinian corpuscles to environmental stress.

Animals↗

The sites for mechano-electric conversion in a Pacinian corpuscle.

The sensory nerve ending in the Pacinian corpuscle is surrounded by a non-nervous capsular structure which occupies about 99.9 per cent of the corpuscle's entire mass. After extirpation of practically all of the non-nervous structure, the sense organ's remains continue to function as a mechano-receptor, namely to produce generator and all-or-nothing potentials in response to mechanical stimuli. Compression of the first intracorpuscular node of Ranvier abolishes the production of "all-or-nothing" potentials in the corpuscle. Graded generator potentials constitute then the only response to mechanical stimulation. This reveals that the first node is the site of origin of the all-or-nothing potential and that the non-myelinated ending is incapable of producing all-or-nothing responses in response to mechanical stimulation. Compression of the entire length of non-myelinated ending suppresses the production of generator potentials. Partial compression of the ending abolishes mechano-responsiveness only of the compressed part. The intact remains of the ending continue to give generator potentials upon mechanical stimulation. This suggests that the generator potential arises at functionally independent membrane parts distributed all over the non-myelinated nerve ending. 24 to 36 hours after denervation of the corpuscle by transection of its sensory axon, no sign of electric activity is detected. Failure of mechano-reception at the nerve ending precedes that of conduction at the degenerating myelinated axon.

Nerve Endings↗

Role of the sympathetic innervation of the pacinian corpuscle.

An investigation was made into the nature of the role played by the noradrenergic innervation of the pacinian corpuscle. Corpuscles of the cat mesentery and mesocolon were used in all experiments. Blockade of noradrenergic beta receptors by dichloroisoproterenol and interference with norepinephrine release by reserpine are each capable of reversibly blocking mechanoelectric transduction by the pacinian corpuscle. The monoamine oxidase inhibitors iproniazid and phenelzine are capable of protecting the transducer from the blocking effects of reserpine. It is concluded that the presence of norepinephrine, as maintained by sympathetic tonus, is required for the afferent nerve terminal of the pacinian corpuscle to be mechanosensitive.

Animals↗

The refractory state of the generator and propagated potentials in a pacinian corpuscle.

A propagated potential produced in the Pacinian corpuscle in response to mechanical stimuli leaves a refractory state of 7 to 10 msec. duration. The refractory state is presumably produced at the first intracorpuscular node of Ranvier. The recovery of receptor excitability for producing an all-or-none response to mechanical stimulation follows the same time course as that of the electrically excited axon. Upon progressive reduction of stimulus interval (mechanical), the propagated potential falls progressively to 75 per cent of its resting magnitude and becomes finally blocked within the corpuscle. A non-propagated all-or-none potential, presumably corresponding to activity of the first node, is then detected. The critical firing level for all-or-none potentials increases progressively during the relative refractory period of the all-or-none potential, as the stimulus interval is shortened. Thus generator potentials up to 85 per cent of a propagated potential can be produced in absence of all-or-none activity. Generator potentials show: gradual over-all increase in amplitude and rate of rise as a function of stimulus strength; constant latency; and spontaneous fluctuations in amplitude. A generator potential leaves a refractory state (presumably at the non-myelinated ending) so that the amplitude of a second generator response which falls on its refractory trail is directly related to the time elapsed after the first generator response and inversely to its amplitude. The generator potential develops independently of any refractory state left by a preceding all-or-none potential.

Nerve Endings↗

[Characteristics of lactate dehydrogenase isoenzyme distribution in Pacinian corpuscles].

The paper deals with the isoenzymic LDG composition in different sections of Pacinian corpuscles. It is found that intracapsular liquid has the aerobic LDG spectrum. The stromal part of the receptor including lamellar capsule structures, inner cone and nerve endings has the anaerobic LDG spectrum. A conclusion is drawn that LDG aerobic LDG spectrum in the intracapsular liquid of Pacinian corpuscles confirms that the liquid is well saturated with oxygen.

Animals↗

Specializations of plasma membranes in Pacinian corpuscles: implications for mechano-electric transduction.

Pacinian corpuscles of cat mesentery were studied with freeze-fracture and thin sectioning methods after chemical fixation. Intramembranous particles (IMPs) exhibit differences in both density and pattern of distribution between the axolemma of the smooth short axis (x-axis) region and that of the axonal spine region of the long axis (y-axis) of the axon terminal. The axolemma of the x-axis has IMPs at a density of 2687 +/- 581 per micron2 (mean +/- S.E.M.), and these particles are 9.0 +/- 1.7 nm (mean +/- S.D.) in diameter. In contrast, the axolemma of the y-axis has a higher density of IMPs (3607 +/- 612 per micron2) which are larger (diameter, 10.0 +/- 1.7 nm). The particle distribution is not homogeneous in x-axis membranes as there are small patchy areas devoid of particles scattered throughout the entire surface. The E-face of the axolemma has a low density of IMPs (approximately 200 per micron2 in both x- and y-axes). However, IMPs in the E-face are smaller (approximately 9 nm) in the x-axis than in the y-axis (approximately 10 nm). The inner core lamellar cells have IMPs at a density of 3276 +/- 739 per micron2 and 553 +/- 169 per micron2 in the P- and E-faces, respectively. The particles are about 10 nm in diameter in both faces. Many gap junctions occur between lamellar cells especially near the clefts, suggesting that hemilamellae of each inner core half are kept at the same electrotonic potential. The outer core lamellar cells have IMPs at a density of 2239 +/- 403 per micron2 and 536 +/- 123 per micron2 in their P- and E-faces, respectively. The particles are approximately 10 nm in diameter in both faces. A noteworthy finding is that tight junctions are prominent at cell-to-cell appositions within individual lamellae, especially in the first and second (or sometimes third) innermost lamellae of the outer core. These tight junctions are considered to be a barrier to the leakage of fluid and/or ions between interlamellar spaces as well as between inner and outer cores. An intermediate cell layer is identified between the inner and outer cores. The connective tissue space of this cell layer corresponds to the endoneurium, indicating that intermediate layer cells are comparable to endoneurial fibroblasts.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

[Effect of magnesium and calcium ions on the electrical activity of Pacinian corpuscles].

The effect of magnesium and calcium ions of the electrical activity of Pacinian corpuscles was studied in isolated decapsulated preparations. The sensitivity of the corpuscles and the amplitude of receptor potential increased in magnesium-rich solution (5-15 mM). The amplitude of receptor potential increased over the first 60 min and then decreased in calcium-free EDTA solution. Magnesium ions slow down or prevent the depressant effects of the lack of calcium on the receptor potential. Divalent cations are supposed to take no part in mechano-electrical transduction conduction in Pacinian corpuscles.

Animals↗