Structure and innervation of the vibrissal follicle-sinus complex in the Australian water rat,Hydromys chrysogaster

Dehnhardt, Guido; Hyvärinen, Heikki; Palviainen, Anne; Klauer, Gertrud

doi:10.1002/(sici)1096-9861(19990906)411:4<550::aid-cne2>3.0.co;2-g

Cited by 61 publications

(51 citation statements)

References 37 publications

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“…When silver staining was inconsistent throughout a section, axon counts were made on half of the 360°cross-section and subsequently multiplied by two. This is possible due to the uniform distribution of axons around the capsule at this level of section in all species reported (Andres, 1966;Stephens et al, 1973;Ling, 1977;Rice et al, 1986;Dehnhardt et al, 1999;Reep et al, 2001).…”

Section: Morphometrics Microstructure and Innervationmentioning

confidence: 92%

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Microstructure and innervation of the mystacial vibrissal follicle‐sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae)

et al. 2005

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Vibrissal follicle-sinus complexes (F-SCs) are sensory receptors of the mammalian integument system. They are best developed within Pinnipedia. The objective of this study was to investigate the F-SCs of bearded seals (Erignathus barbatus) for benthic foraging adaptations. Bearded seals possessed approximately 244 mystacial F-SCs. In this species, F-SCs consisted of an outer dermal capsule (DC) surrounding a blood sinus system [upper cavernous sinus (UCS), ring sinus (RS), and lower cavernous sinus (LCS)] and concentric rings of epidermal tissue. The UCS comprised up to 62% of the F-SC length and may function as thermal protection for mechanoreceptors. A large asymmetrical ringwulst was located in the RS. A deep vibrissal nerve penetrated the DC at its base and terminated on mechanoreceptors in the epidermal tissues of the LCS and RS. The mean number of myelinated axons per F-SC was 1,314 (range, 811-1,650) and was among the highest number of axons per F-SC reported to date. An estimated mean number of 320,616 myelinated axons innervate the entire mystacial vibrissal array. Merkel-Neurite complexes (MNCs) and small simple laminated corpuscles were found in the region of the LCS. Myelinated axons also terminated on MNCs and lanceolate endings apical to the ringwulst. The number of F-SCs, their geometry in the mystacial region, the number of myelinated axons per F-SC, and the distribution of mechanoreceptors support the premise that pinniped vibrissae are sensitive active-touch receptor systems, and that structural differences in bearded seals, relative to other phocids, may be adaptations for benthic foraging.

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Section: Morphometrics Microstructure and Innervationmentioning

confidence: 92%

“…Third, the number of myelinated axons per F-SCs of terrestrial taxa is much less than that of aquatic mammals (Hyvä rinen, 1995;Dehnhardt et al, 1999). Terrestrial mammals such as rodents, rabbits, cats, and monkeys receive only ϳ 200 myelinated axons per F-SC or less (Halata, 1975;Halata and Munger, 1980;Rice et al, 1986Rice et al, , 1997.…”

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confidence: 99%

Microstructure and innervation of the mystacial vibrissal follicle‐sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae)

et al. 2005

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“…Aspects of FSC anatomy (Dö rfl 1985; Rice et al 1986;Dehnhardt et al 1999;Ebara et al 2002) are distilled in figure 1a. In the rat, the follicle capsule is fairly rigid (Ebara et al 2002), so we modelled it as a rigid component.…”

Section: Model Development (A) Overviewmentioning

confidence: 99%

Empirically inspired simulated electro-mechanical model of the rat mystacial follicle-sinus complex

Mitchinson

Gurney

Redgrave

et al. 2004

Proc. R. Soc. Lond. B

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In whiskered animals, activity is evoked in the primary sensory afferent cells (trigeminal nerve) by mechanical stimulation of the whiskers. In some cell populations this activity is correlated well with continuous stimulus parameters such as whisker deflection magnitude, but in others it is observed to represent events such as whisker-stimulator contact or detachment. The transduction process is mediated by the mechanics of the whisker shaft and follicle-sinus complex (FSC), and the mechanics and electro-chemistry of mechanoreceptors within the FSC. An understanding of this transduction process and the nature of the primary neural codes generated is crucial for understanding more central sensory processing in the thalamus and cortex. However, the details of the peripheral processing are currently poorly understood. To overcome this deficiency in our knowledge, we constructed a simulated electro-mechanical model of the whisker-FSC-mechanoreceptor system in the rat and tested it against a variety of data drawn from the literature. The agreement was good enough to suggest that the model captures many of the key features of the peripheral whisker system in the rat.

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“…In pinnipeds, however, the follicle-sinus-complex (FSC) is the largest of all mammals. They can reach 2cm in length, whereas those on terrestrial mammals of similar size are much shorter (for example, those in the leopard Panthera pardus are 6.5mm long) [22]. A schematic and photo of the FSC are shown in Figure 1-8.…”

Section: Under the Skin: Structurementioning

confidence: 99%

Passive wake detection using seal whisker-inspired sensing

Beem¹

2015

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This thesis is motivated by a series of biological experiments that display the harbor seal's extraordinary ability to track the wake of an object several seconds after it has swum by. They do so despite having auditory and visual cues blocked, pointing to use of their whiskers as sensors of minute water movements. In this work, I elucidate the basic fluid mechanisms that seals may employ to accomplish this detection. Key are the unique flow-induced vibration properties resulting from the geometry of the harbor seal whisker, which is undulatory and elliptical in cross-section.First, the vortex-induced vibration (VIV) characteristics of the whisker geometry are tested. Direct force measurements and flow visualizations on a rigid whisker model undergoing a range of 1-D imposed oscillations show that the geometry passively reduces VIV (factor of > 10), despite contributions from effective added mass and damping. Next, a biomimetic whisker sensor is designed and fabricated. The rigid whisker model is mounted on a four-armed flexure, allowing it to freely vibrate in both in-line and crossflow directions. Strain gauges on the flexure measure deflections at the base. Finally, this device is tested in a simplified version of the fish wake -seal whisker interaction scenario. The whisker is towed behind an upstream cylinder with larger diameter. Whereas in open water the whisker exhibits very low vibration when its long axis is aligned with the incoming flow, once it enters the wake it oscillates with large amplitude and its frequency coincides with the Strouhal frequency of the upstream cylinder. This makes the detection of an upstream wake as well as an estimation of the size of the wake-generating body possible. A slaloming motion among the wake vortices causes the whisker to oscillate in this manner. The same mechanism has been previously observed in energy-extracting foils and trout actively swimming behind bluff cylinders in a stream. Dave, Jason, Gabe, Pablo, Remi, and Yahya were postdocs when we first met.Thank you for being approachable and sharing much needed advice all along the way.Your love of science has inspired me to be more inquisitive.Brandon, Chris, Matthew, and Patrick were undergrads or high school students who spent their summers working in the Tow Tank with me. Thanks for giving me the chance to practice being a mentor, moving this research forward a lot faster than I could do on my own, and helping me lift the mega-whisker in and out of the tank! May you all keep on building and exploring.Thanks to Kathy Streeter and the New England Aquarium staff for helping me understand more about real harbor seals. They graciously collected shed whisker specimens and allowed me to take many close-up pictures of their seals.Thanks to all the people who helped me prepare for and make it through research cruises: Eric Hayden, Terry Hammar, and Hanu Singh for contributing their expertise 5 to help me make my first ocean-ready sensor, all parties involved in the first UNOLS Chief Scientist Training Cruise se...

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Structure and innervation of the vibrissal follicle-sinus complex in the Australian water rat,Hydromys chrysogaster

Cited by 61 publications

References 37 publications

Microstructure and innervation of the mystacial vibrissal follicle‐sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae)

Microstructure and innervation of the mystacial vibrissal follicle‐sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae)

Empirically inspired simulated electro-mechanical model of the rat mystacial follicle-sinus complex

Passive wake detection using seal whisker-inspired sensing

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