Differential and morphogenetic potential of rat dermal papilla cells

Dermal papilla (DP) cells were isolated from rat vibrissae and put into a culture. The homogeneity of the obtained culture was confirmed using immunohistochemical staining with antibodies specific for this type of cell extracellular matrix protein (versican) and staining for alkaline phosphatase. It was demonstrated that the rat vibrissae DP cell culture participates in the development of hair follicles de novo. The ability of the DP culture cells to differentiate in neurons and glia was proved.     

Whisker growth in wild Eurasian badgers Meles meles: implications for stable isotope and bait marking studies

The use of biomarkers such as stable isotopes to study the foraging ecology and movement of animals is a rapidly expanding area of research. With respect to mammals, the analysis of inert keratinous tissue such as whiskers (vibrissae) is particularly attractive as they can be sequentially sampled to provide a long-term time series of individual movement or diet. However, in order to interpret data from such tissues researchers require details of growth rates and patterns, and also how these vary within populations. In this study, we use the fluorescent biomarker Rhodamine B to measure vibrissa growth rate and patterns in a wild population of Eurasian badgers. In addition, we compare stable isotope ratio values of blood and vibrissae in order to test whether vibrissae are retained for long periods following growth. We found that badger vibrissae grow at an average rate of 0.43 mm?day^?1 (range 0.23–0.83) such that single vibrissae sampled for stable isotope analysis contain an average of 104 days of ecological data. Age, sex and body condition did not affect growth rate, and there was no evidence of consistent individual differences in growth rate or long-term retention of vibrissae following growth. However, variation in growth rate within the population suggest that the temporal scales reflected in vibrissae may vary both between and within individuals, such that results are not always directly, temporally comparable. This research provides useful information for any future research using vibrissae in combination with biomarkers to study mammalian ecology.     

Effect of vibrissae removal on search accuracy in the water maze

In two experiments the vibrissae were clipped on either the left, the right or both sides, and the rats were trained to find a submerged platform in the Morris water maze. In both experiments, animals without vibrissae on both sides or on the left consistently spent significantly more time in the 'counter' area twice the platform diameter in size, surrounding the submerged platform, than intact controls. Counter preference was not as consistent across experiments in rats with right vibrissae removed. These results suggest that the vibrissae are required for proprioceptive location of the platform itself, but not for proximal search accuracy. Since ischaemic damage to hippocampal CA1 pyramidal cells has also been reported to prolong counter search during training, the results support the suggestion that impaired hippocampal processing of proprioceptive information from the vibrissae may contribute to the increased latency to find the platform shown by ischaemic rats.     

Comparative histomorphology of intrinsic vibrissa musculature among primates: implications for the evolution of sensory ecology and “face touch”

Macrovibrissae are specialized tactile sensory hairs present in most mammalian orders, used in maxillary mechanoreception or “face touch.” Some mammals have highly organized vibrissae and are able to “whisk” them. Movement of vibrissae is influenced by intrinsic vibrissa musculature, striated muscle bands that attach directly to the vibrissa capsule. It is unclear if primates have organized vibrissae or intrinsic vibrissa musculature and it is uncertain if they can move their vibrissae. The present study used histomorphological techniques to compare vibrissae among 19 primates and seven non‐primate mammalian taxa. Upper lips of these mammals were sectioned and processed for histochemical analysis. While controlling for phylogenetic effects the following hypotheses were tested: 1) mammals with well‐organized vibrissae possess intrinsic vibrissa musculature and 2) intrinsic vibrissa musculature is best developed in nocturnal, arboreal taxa. Our qualitative analyses show that only arboreal, nocturnal prosimians possess intrinsic musculature. Not all taxa that possessed organized vibrissae had intrinsic vibrissa musculature. Phylogenetic comparative analyses revealed a 70% probability that stem mammals, primates, and haplorhines possessed intrinsic vibrissa musculature and well‐organized vibrissae. These two traits most likely coevolved according to a discrete phylogenetic analysis. These results indicate that nocturnal, arboreal primates have the potential to more actively use their vibrissae in spatial recognition and navigation tasks than diurnal, more terrestrial species, but there is a clear phylogenetic signal involved in the evolution of primate vibrissae and “face touch.” Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.     

Cortical potentials evoked by mechanical stimulation of different number of vibrissae of the rat

Distribution maps of cortical potentials evoked by mechanical stimulation of different number of contralateral vibrissae were studied. It was found that stimulation of all the contralateral vibrissae led to more extensive activation than the barrel field in the somatosensory cortex. The activation was most widespread when all the vibrissae were synchronously deflected. With reduction of the number of synchronously stimulated whiskers the activated cortical area did not decrease in parallel. Deflection of only a few whiskers activated significantly smaller cortical areas.     

Basic fibroblast growth factor-like immunoreactivity in the rat trigeminal sensory system and peri-oral skin with vibrissae

We have characterized an antiserum against basic fibroblast growth factor (bFGF) by immunoblot, investigated the location of bFGF-like immunoreactivity (bFGF-IR) in the trigeminal sensory system and perioral skin endowed with vibrissae, and demonstrated the site of bFGF mRNA expression in the vibrissae by in situ hybridization histochemistry. Light-microscopic immunohistochemistry has demonstrated that bFGF-IR is present not only in trigeminal ganglion neurons and their central and peripheral processes, but also in cells of the matrix, external root sheath and papillae of vibrissae and the stratum basale of the stratified squamous epithelium of the skin. Electron microscopy has revealed intense bFGF-IR mainly in cytoplasmic regions, other than the lumen of rough endoplasmic reticulum and the Golgi apparatus, in trigeminal ganglion neurons, in fibroblast-like cells in the papillae, and in capsules of vibrissae. In contrast, actively proliferating and/or differentiating cells in the matrix of vibrissae have intensely stained euchromatin and weakly labeled cytoplasm that, unlike that of the aforementioned cells, contain immunoreaction products in discrete spots less than 100 nm in diameter, implying the generation of different molecular forms of bFGF in cells of the matrix and papillae. Moreover, the accumulation of bFGF in the euchromatin appears to take place in cells at non-mitotic stages (possibly interphases), characterized by a conspicuous nucleolus and well-developed nuclear envelope. A digoxigenin-labeled cRNA probe for the demonstration of bFGF mRNA gives conspicuous hybridization signals mainly in the matrix of vibrissae. These findings suggest that bFGF is involved in the growth and differentiation of matrix cells during certain periods of the cell cycle and that it acts as a non-mitogenic mediator in the adult trigeminal sensory system.     

Diving in darkness: whiskers as sense organs of the ringed seal (Phoca hispida saimensis)

Underwater vocalization and the functional structure of different vibrissae of the ringed seal ( Phoca hispida saimensis ) of Lake Saimaa, Eastern Finland, were studied. These seals live in darkness under the ice cover for several months during the year. It is known that blind seals are managing well in the lake. Visibility under water in some parts of the area where the seals live is only 2 m. It is suggested that echolocation is used in orientation and feeding. The Saimaa seal has click and click trial underwater vocalizations. However, both the frequency and intensity of the vocalization are low compared with, for example, those of dolphins. The structural adaptations for underwater sound localization are also not well developed.
The ringed seal has, however, extremely well-developed vibrissae. The innervation of one vibrissa is more than 10 times greater than normally found in mammals. The main structural deviations from normal mammalian vibrissae are: (1) an upper cavernous sinus, (2) a groove in the wall of the capsule at the level of the lower cavernous sinus, (3) elasticity of the connective tissue bands fixing the hair root to the capsule in the lower cavernous sinus and especially (4) the structure and innervation of the ring sinus area. Sensory elements are situated upon the glassy membrane on the surface of the outer rootsheath and in the basal cell layer of the outer rootsheath which is like a sensory epithelium. Below this epithelium a layer of liquid or gelatinous material and large amounts of glycogen are found. This sensory epithelium is especially well developed in the superciliary vibrissae. These vibrissae are protruded some millimetres when the seals are attentive. It is suggested that the vibrissae also sense sounds, which are transmitted to the sensory elements by tissue conduction through the capsule wall and via the blood sinuses. The seals may possibly detect compressional waves with the vibrissae.     

Responses of neurons in the vibrissae projection area of the cat somatosensory cortex to afferent activation

Responses of 375 primary somatosensory cortical neurons located in the projection area of the vibrissae to electrical stimulation of the infraorbital nerve and also to adequate stimulation of the vibrissae were investigated in unanesthetized cats immobilized with tubocurarine. Stimulation of the nerve and vibrissae most frequently evoked synaptic responses in the neurons, in the form of a short EPSP followed by an IPSP or, less frequently, as a primary IPSP; during extracellular recordings corresponding changes were observed in spike activity. In response to stimulation of the vibrissae, initial inhibition was found more often than to stimulation of the nerve (in 45 and 16% of neurons respectively). The difference between the minimal values of latent periods of IPSP and EPSP evoked by stimulation of the infraorbital nerve was 0.8 msec in different neurons, and the difference between the mean values 1.4 msec. Directional sensitivity of the cortical neurons was demonstrated (to a change in the direction of deflection of the vibrissae). Neurons located close together could differ in the character of their directional sensitivity during stimulation of the same vibrissae. It is concluded that short-latency inhibition arising in the primary projection area of the cat somatosensory cortex is predominantly afferent and not recurrent. The probable mechanisms of directional sensitivity of the neurons studied are discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSSR, Kiev. Translated from Neirofiziologia, Vol. 11, No. 6, pp. 550–559, November, 1979.     

Hairs and vibrissae in the Rhinocerotidae

Evidence is reviewed and observations are submitted concerning the occurrence and distribution of body hair in rhinoceroses. Absence of externally visible hair is shown to be not necessarily indicative of absence of hair follicles and to be part of a morphological cooling mechanism necessitated by the dynamics of the large body. Eyelashes are shown to be present on the lower eyelid of three species at least. The post-natal absence of all groups of facial vibrissae is confirmed for all rhinoceros forms, but a genal vibrissa is recorded for a Diceros foetus. Observations are submitted upon the hitherto undescribed histology of Diceros skin.     

The role of vibrissal sensing in forelimb position control during travelling locomotion in the rat (Rattus norvegicus,Rodentia)

In the stem lineage of therians, a comprehensive reorganization of limb and body mechanics took place to provide dynamic stability for rapid locomotion in a highly structured environment. At what was probably the same time, mammals developed an active sense of touch in the form of movable mystacial vibrissae. The rhythmic movements of the limbs and vibrissae are controlled by central pattern-generating networks which might interact with each other in sensorimotor control. To test this possible interaction, we studied covariation between the two by investigating speed-dependent adjustments in temporal and spatial parameters of forelimb and vibrissal kinematics in the rat. Furthermore, the possible role of carpal vibrissae in connecting the two oscillating systems was explored. We compared locomotion on continuous and discontinuous substrates in the presence and absence of the mystacial or/and carpal vibrissae across a speed range of 0.2–0.5 m/s and found that a close coupling of the kinematics of the two oscillating systems appears to be precluded by their differential dependence on the animal's speed. Speed-related changes in forelimb kinematics mainly occur in temporal parameters, whereas vibrissae change their spatial excursion. However, whisking frequency is always high enough that at least one whisk cycle falls into the swing phase of the limb, which is the maximum critical period for sensing the substrate on which the forepaw will be placed. The influence of tactile cues on forelimb positional control is more subtle than expected. Tactile cues appear to affect the degree of parameter variation but not average parameters or the failure rate of limbs during walking on a perforated treadmill. The carpal vibrissae appear to play a role in sensing the animal's speed by measuring the duration of the stance phase. The absence of this cue significantly reduces speed-related variation in stride frequency and vibrissal protraction.     

Movements of the cranial vibrissae in the Golden hamster (Mesocricetus auratus)

Vibrissae are highly refined vibrotactile receptors that are present on most mammals. The Golden hamster exhibits three different behaviours of its mystacial, supraorbital, and genal vibrissae. During rest, all the vibrissae are reclined and motionless. When hamsters are alert, the vibrissae are partly or fully erect and essentially motionless. During active investigation, the mystacial vibrissae "whisk" or "sweep" through antero–posterior excursions. The genal vibrissa moves only slightly in periodic erection. The supraorbital vibrissae carry through a wide erection arc and have limited excursions with movements of the upper eyelid. The mystacial vibrissae whisk quickly (about 16 sweepsls). Whisking is divisible into contact (relatively high amplitude, low frequency), non–contact (relatively low amplitude, high frequency), and double–pump (combination contact and non–contact) types, and can be either bilaterally symmetric or asymmetric. The dimensions of the mystacial territory around the snout change throughout whisking due to coordinated changes in the shape of the mystacial pad and the tilting of the vibrissae relative to the pad. Such differential movements have implications for sensory physiology as they point to an ability for fine sensory monitoring of the environment.     

Immunocytochemical analysis of calcitonin gene-related peptide and vasoactive intestinal polypeptide in Merkel cells and cutaneous free nerve endings of cats

Summary Calcitonin gene-related peptide (CGRP)-and vasoactive intestinal polypeptide (VIP)-immunoreactivity were observed to coexist in Merkel cells of cats. No differences in peptide content were found between Merkel cells located in epithelia of the hard palate, in hairy and glabrous skin of the upper lip, and in vibrissae follicles. CGRP-and VIP-immunoreactive nerve fibres were also found near CGRP/VIP-immunoreactive Merkel cells. In the vibrissae follicles some CGRP-and VIP-immunoreactive nerve terminals end abutting on the glassy membrane. Other CGRP immunoreactive nerve fibres penetrate the epithelium of the skin and end within it. Electron microscopy of vibrissae follicles revealed that Merkel cell neuntes are not immunostained and that immunostained nerve fibres form unmyelinated bundles before ending freely. Thus, CGRP-and VIP immunoreactive nerve fibres in cat skin do not end as Merkel cell neuntes but as different kinds of free nerve endings.     

On the histology and histochemistry of the snout and vibrissae of the common shrew (Sorex araneus L.)

Summary The structure of the snout and tactile hair system of the common shrew (Sorex araneus) and the distribution of cholinesterase and alkaline phosphatase activity were studied. The structure of the vibrissae is exceptional compared with that of other mammals studied. Differences are the attachment system of hair follicle to the capsule, the impossibility of dividing the blood sinus clearly into cavernous sinus and ring sinus, the lack of continuous ring-wulst, clear constriction in the outer root sheath at the neck of hair follicle and some specialized structures connected with this. Alkaline phosphatase was not found in the nervous structures of the vibrissae but cholinesterase activity occurs at least in two different structures upon or in the outer root sheath of the hair follicle. The role of these structures and the significance of vibrissae to the shrew is discussed.     

La detection des objets en milieux aquatique et aerien par le desman des pyrenees (Galemys Pyrenaicus)

The Pyrenean desman (Insectivora, Talpidae) is a nocturnal species which can move without difficulty amongst the obstacles found in the mountain torrents—whether in total immersion or on the water surface—despite the fact that it is almost blind. The present experiments have attempted to study its capacity to detect obstacles at or below water level. Results have confirmed our hypothesis that the mode of detection is certainly not visual nor olfactive, but probably related to vibration, i.e. tactile and/or acoustic. This view is supported by the desman's hearing capacity and by two highly sensitive organs it possesses, the Eimer's organ and the vibrissae system.     

Effects of neonatal axoplasmic transport attenuation on the response properties of vibrissae-sensitive neurons in the trigeminal principal sensory nucleus of the rat

We have previously shown that attenuation of axoplasmic transport by application of vinblastine to the developing infraorbital nerve (ION) results in a loss of central vibrissae-related patterns that is not accompanied by changes in the receptive field sizes for the V primary afferents innervating the whisker follicles. The present study examines the relationship between the loss of central vibrissae-related patterns and alterations in the response properties of neurons in the V principal sensory nucleus (PrV) of adult rats that sustained application of vinblastine to the ION at birth. Absence of histochemically demonstrable vibrissae-related patterns in PrV resulted in only modest changes in the receptive fields and response properties of vibrissae-sensitive neurons in this nucleus that projected to the contralateral thalamus. Response latencies to electrical activation of the V ganglion were similar in treated and untreated animals. The mean receptive field size was significantly increased from 1.3 +/- 0.7 vibrissae in controls to 1.7 +/- 0.9 vibrissae in vinblastine-treated animals, and the percentage of cells yielding a tonic response to vibrissae deflection was markedly reduced (p < 0.01 for both measures). Phasically responding cells recorded in vinblastine-treated animals showed a significant reduction in the mean number of spikes per stimulus following deflection of the vibrissae in either the preferred or non-preferred direction relative to cells recorded in normal animals (p < 0.05). The present results indicate that disruption of the normal vibrissae-related aggregates of neurons in PrV by application of vinblastine to the ION has limited effects on the functional representation of the vibrissae in this nucleus.     

Effects of neonatal axoplasmic transport attenuation on the response properties of vibrissae-sensitive neurons in the trigeminal principal sensory nucleus of the rat

We have previously shown that attenuation of axoplasmic transport by application of vinblastine to the developing infraorbital nerve (ION) results in a loss of central vibrissae-related patterns that is not accompanied by changes in the receptive field sizes for the V primary afferents innervating the whisker follicles. The present study examines the relationship between the loss of central vibrissae-related patterns and alterations in the response properties of neurons in the V principal sensory nucleus (PrV) of adult rats that sustained application of vinblastine to the ION at birth. Absence of histochemically demonstrable vibrissae-related patterns in PrV resulted in only modest changes in the receptive fields and response properties of vibrissae-sensitive neurons in this nucleus that projected to the contralateral thalamus. Response latencies to electrical activation of the V ganglion were similar in treated and untreated animals. The mean receptive field size was significantly increased from 1.3 &#45 0.7 vibrissae in controls to 1.7 &#45 0.9 vibrissae in vinblastine-treated animals, and the percentage of cells yielding a tonic response to vibrissae deflection was markedly reduced (p < 0.01 for both measures). Phasically responding cells recorded in vinblastine-treated animals showed a significant reduction in the mean number of spikes per stimulus following deflection of the vibrissae in either the preferred or non-preferred direction relative to cells recorded in normal animals (p < 0.05). The present results indicate that disruption of the normal vibrissae-related aggregates of neurons in PrV by application of vinblastine to the ION has limited effects on the functional representation of the vibrissae in this nucleus.     

Hair type,intake, and detection method influence Rhodamine B detectability

Rhodamine B (RB) is a popular bait-marking tool in wildlife research, although its use has required many assumptions about marking reliability. These assumptions have limited dosage ranges and detection methods in research applications. Identification of alternate detection methods, hair types, and dosage rates could create new opportunities for RB use and potentially reduce adverse effects on target animals. We examined the relationship between hair types, dosage rate, and detection method for RB applications using black rats (Rattus rattus) in laboratory settings. We gave study animals varying doses of RB, and examined vibrissae and guard hairs for the detection of RB bands using ambient light, ultraviolet (UV) light, and fluorescence microscopy techniques. Fluorescence microscopy detected more RB marked hairs than UV light or ambient light. Fluorescence microscopy was more sensitive to RB dose rate detection; with receiver operating characteristic curves suggesting that the minimum dose rates at which RB intake can be correctly detected are 3.9 and 33 mg/kg for vibrissae and guard hairs, respectively. Guard hair RB detection was less reliable under ambient light and UV lamps, but equally detectable as vibrissae under fluorescence microscopy. Our results confirmed the interrelationship between dosage and detection methods in the efficacy of bait markers. We demonstrated that guard hairs can be a reliable hair type for the detection of RB. This application is less invasive than sampling animal tissues to detect bait uptake. © 2012 The Wildlife Society.     

Effect of Angle on Flow-Induced Vibrations of Pinniped Vibrissae

Two types of vibrissal surface structures, undulated and smooth, exist among pinnipeds. Most Phocidae have vibrissae with undulated surfaces, while Otariidae, Odobenidae, and a few phocid species possess vibrissae with smooth surfaces. Variations in cross-sectional profile and orientation of the vibrissae also exist between pinniped species. These factors may influence the way that the vibrissae behave when exposed to water flow. This study investigated the effect that vibrissal surface structure and orientation have on flow-induced vibrations of pinniped vibrissae. Laser vibrometry was used to record vibrations along the whisker shaft from the undulated vibrissae of harbor seals (Phoca vitulina) and northern elephant seals (Mirounga angustirostris) and the smooth vibrissae of California sea lions (Zalophus californianus). Vibrations along the whisker shaft were measured in a flume tank, at three orientations (0°, 45°, 90°) to the water flow. The results show that vibration frequency and velocity ranges were similar for both undulated and smooth vibrissae. Angle of orientation, rather than surface structure, had the greatest effect on flow-induced vibrations. Vibration velocity was up to 60 times higher when the wide, flat aspect of the whisker faced into the flow (90°), compared to when the thin edge faced into the flow (0°). Vibration frequency was also dependent on angle of orientation. Peak frequencies were measured up to 270 Hz and were highest at the 0° orientation for all whiskers. Furthermore, CT scanning was used to quantify the three-dimensional structure of pinniped vibrissae that may influence flow interactions. The CT data provide evidence that all vibrissae are flattened in cross-section to some extent and that differences exist in the orientation of this profile with respect to the major curvature of the hair shaft. These data support the hypothesis that a compressed cross-sectional profile may play a key role in reducing self-noise of the vibrissae.     

Evidence for Functional Groupings of Vibrissae across the Rodent Mystacial Pad

During natural exploration, rats exhibit two particularly conspicuous vibrissal-mediated behaviors: they follow along walls, and “dab” their snouts on the ground at frequencies related to the whisking cycle. In general, the walls and ground may be located at any distance from, and at any orientation relative to, the rat’s head, which raises the question of how the rat might determine the position and orientation of these surfaces. Previous studies have compellingly demonstrated that rats can accurately determine the horizontal angle at which a vibrissa first touches an object, and we therefore asked whether this parameter could provide the rat with information about the pitch, distance, and yaw of a surface relative to its head. We used a three-dimensional model of the whisker array to construct mappings between the horizontal angle of contact of each vibrissa and every possible (pitch, distance, and yaw) configuration of the head relative to a flat surface. The mappings revealed striking differences in the patterns of contact for vibrissae in different regions of the array. The exterior (A, D, E) rows provide information about the relative pitch of the surface regardless of distance. The interior (B, C) rows provide distance cues regardless of head pitch. Yaw is linearly correlated with the difference between the number of right and left whiskers touching the surface. Compared to the long reaches that whiskers can make to the side and below the rat, the reachable distance in front of the rat’s nose is relatively small. We confirmed key predictions of these functional groupings in a behavioral experiment that monitored the contact patterns that the vibrissae made with a flat vertical surface. These results suggest that vibrissae in different regions of the array are not interchangeable sensors, but rather functionally grouped to acquire particular types of information about the environment.