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 innervated by sensory neurons that convert mechanical pressure into electrical signals that, in animals, a ...

discovered by

anatomist Anatomy () is the branch of biology concerned with the study of the 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 science, having it ...

Georg Meissner (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) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

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 a ...

. 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), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that o ...

. 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 is a lipid-rich material that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can ...

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 cells, olfactory en ...

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, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

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 limb of the body and a type of digit, an organ of manipulation and sensation found in the hands of most of the Tetrapods, so also with humans and other primates. Most land vertebrates have five fingers ( Pentadactyly). Chamber ...

lip The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

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 hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rel ...

within the dermal papillae.

Comparison with other receptors

Feelings of deep

(from a poke, for instance) are generated from

lamellar corpuscle Pacinian corpuscle or lamellar corpuscle or Vater-Pacini corpuscle; is one of the four major types of mechanoreceptors (specialized nerve ending with adventitious tissue for mechanical sensation) found in mammalian skin. This type of mechanorece ...

s (the only other type of phasic tactile mechanoreceptor), which are located deeper in the dermis, and some free nerve endings. Also, tactile corpuscles do not detect noxious stimuli; this is signaled exclusively by free nerve endings.

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 (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 ...

, 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. Any physical deformation of the corpuscle will cause

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

ions to enter it, creating an

action potential An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells ...

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