Tactile corpuscles or Meissner's corpuscles are a type of

mechanoreceptor A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are located on sensory neurons that convert mechanical pressure into action potential, electrical signals tha ...

discovered by

anatomist Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...

Georg Meissner George Meissner (19 November 1829 – 30 March 1905) was a German anatomist and physiologist born in Hanover. He studied medicine at the University of Göttingen, where he worked closely with Rudolf Wagner (1806–1864). In 1851 he accompa ...

(1829–1905) and Rudolf Wagner. This corpuscle is a type of

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons). Nerves have historically been considered the basic units of the peripheral nervous system. A nerve provides a common pathway for the Electrochemistry, electrochemical nerv ...

ending in the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

that is responsible for sensitivity to

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

. In particular, they have their highest sensitivity (lowest threshold) when sensing vibrations between 10 and 50

hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or Cycle per second, cycle) per second. The hertz is an SI derived unit whose formal expression in ter ...

. They are rapidly adaptive receptors. They are most concentrated in thick hairless skin, especially at the finger pads.

Structure

Tactile corpuscles are encapsulated

myelin Myelin Sheath ( ) is a lipid-rich material that in most vertebrates surrounds the axons of neurons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. The myelinated axon can be lik ...

ated

endings, surrounded by

Schwann cell Schwann cells or neurolemmocytes (named after German physiologist Theodor Schwann) are the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS, also include Satellite glial cell, satellite ...

s. The encapsulation consists of flattened supportive cells arranged as horizontal lamellae surrounded by a

connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...

capsule. The corpuscle is 30–140 μm in length and 40–60 μm in diameter. A single nerve fiber meanders between the lamellae and throughout the corpuscle.

Location

They are distributed on various areas of the

, but concentrated in areas especially sensitive to light touch, such as the

finger A finger is a prominent digit (anatomy), digit on the forelimbs of most tetrapod vertebrate animals, especially those with prehensile extremities (i.e. hands) such as humans and other primates. Most tetrapods have five digits (dactyly, pentadact ...

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

s and male prepuce. More specifically, they are primarily located in glabrous skin just beneath the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...

within the

dermal papillae The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided ...

Comparison with other receptors

Feelings of deep

(from a poke, for instance) are generated from

lamellar corpuscle The Pacinian corpuscle (also lamellar corpuscle, or Vater–Pacini corpuscle) is a low-threshold mechanoreceptor responsive to vibration or pressure, found in the skin and other internal organs. In the skin it is one of the four main types of cuta ...

s (the only other type of phasic tactile mechanoreceptor), which are located deeper in the dermis, and some

free nerve ending A free nerve ending (FNE) or bare nerve ending, is an unspecialized, afferent nerve fiber sending its signal to a sensory neuron. ''Afferent'' in this case means bringing information from the body's periphery toward the brain. They function as cu ...

s. Also, tactile corpuscles do not detect

noxious stimuli A noxious stimulus is a stimulus strong enough to threaten the body's integrity (i.e. cause damage to tissue). Noxious stimulation induces peripheral afferents responsible for transducing pain (including A-delta and C- nerve fibers, as well a ...

; this is signaled exclusively by

Development

The number of tactile corpuscles per square millimeter of human skin on the fingertips drops fourfold between the ages of 12 and 50. The rate at which they are lost correlates well with the age-related loss in touch sensitivity for small probes.

Function

Tactile corpuscles are rapidly adapting mechanoreceptors. They are sensitive to shape and textural changes in exploratory and discriminatory touch. Their acute sensitivity provides the neural basis for reading Braille text. Because of their superficial location in the

dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...

, these corpuscles are particularly sensitive to touch and vibrations, but for the same reasons, they are limited in their detection because they can only signal that something is touching the skin. They also contribute to two-point discrimination, allowing the skin to detect stimuli at closely spaced points. Any physical deformation of the corpuscle will cause

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

ions to enter it, creating an

action potential An action potential (also known as a nerve impulse or "spike" when in a neuron) is a series of quick changes in voltage across a cell membrane. An action potential occurs when the membrane potential of a specific Cell (biology), cell rapidly ri ...

in the corpuscle's nerve fiber. Since they are rapidly adapting or phasic, the action potentials generated quickly decrease and eventually cease (this is the reason one stops "feeling" one's clothes). If the stimulus is removed, the corpuscle regains its shape and while doing so (i.e.: while physically reforming) causes another volley of action potentials to be generated.

Additional images

Skin.png, "Meissner's corpuscle" labeled at upper right Image:Gray940.png, Diagrammatic sectional view of the skin. Image:WVSOM Meissner's corpuslce.JPG, light micrograph

References

Sources

* *

External links

* Donald L. Rubbelke D.A
Tissues of the Human Body: An Introduction. McGraw-Hill. 1999 Meissner's and Pacinian corpuscles
* Dawn A. Tamarkin, Ph.D

* - "Integument pigmented skin, Meissner's corpuscles " * - "Meissner's Tactile Corpuscle"

{{Authority control Sensory receptors