Ruffini’s corpuscles: what are these receptors and how they work

Ruffini Corpuscles These are types of mechanoreceptors that are particularly responsible for temperature perception, which could be considered a sub-component of the sense of touch.

Although these are very small cells, the truth is that without them we could not correctly detect when we are in an environment where we can constipate or die from a heat wave, besides being important in sensing. of body stretching.

Neurobiology has been tasked with studying this component of the human sensory system, describing and classifying it as described in this article. Let’s see how Ruffini’s corpuscles are and work below.

    What are Ruffini’s corpuscles?

    Ruffini’s corpuscles, also called bulbous corpuscles, these are cells that detect sensory stimuli in the skin, Having an important role in the constitution and training of the sense of touch. They take their name from the name of the person who discovered them, Angelo Ruffini, a remarkable Italian doctor and biologist.

    These are types of mechanoreceptors that they detect temperature changes and stretching of the skin. They have the ability to detect signals within very small receptive fields, which puts them in the category of type I mechanoreceptors. They are not very numerous or large in size.

    It has been shown that deep skin changes due to scars, degenerative processes, aging or poor joint arrangement can alter the location of these corpuscles.

    What do these cells look like?

    Ruffini Corpuscles they are formed of many free nerve endings, Which originate in a myelinated axon and constitute a cylindrical-shaped structure. This structure, which has the appearance of a capsule, the nerve endings are organized by anchoring between the collagen fibers of the connective tissue. The axon demyelinates and later branches off in half, before forming the branching nerve endings.

    Despite this, it must be said that there are differences between the corpuscles of Ruffini in hairy skin and those found in hairless skin. An example of this is in the penis, particularly in the foreskin, where the corpuscles originate from a single axon that branches out several times before fully demyelinating in the connective tissue capsule.

    On the other hand, in the case of hair with hair, the axon takes the form of a spiral approaching the hair follicle just below the sebaceous gland, where it branches out and loses myelin.

      Where are they?

      Ruffini’s corpuscles are found on both hairy and hairless skin, that is, in which there are no hairs, as well as in the hypodermis and epidermis. They are also found in non-superficial structures, such as the menisci, cruciate and lateral ligaments and joint capsules. These cells can be found in most mammals.

      However, and although they are present all over the skin, there are differences in the level at which these corpuscles are found depending on whether there is hair or not. In the case of hairless surfaces, such as the palms and fingers, soles of the feet, lips, penis and pubis, these cells are located at the reticular layer of the epidermis.

      Although in the case of structures in which yes there is hair, the Ruffini corpuscles are also in the reticular layer of the epidermis, between the hair and the hair, in addition to being located in the connective weaving capsule that covers the part of hair that is inserted some depth into the skin. The set formed by this type of cell and the capsule is called the pilo-Ruffini complex.

      In the animal world, in addition to the areas we have mentioned, these corpuscles are found in somewhat particular places. In the case of some primates, they have been found associated with regions of the dermis close to the hairs found in the nasal lining. In birds and some mammals, Ruffini cells have been seen to be found in the joints, but only in the fibrous part and ligaments.

      What function do they have?

      The main function of Ruffini’s corpuscles is the perception of temperature changes, in addition to stretching the skin. too much they can perceive the continuous deformation of the skin and internal tissues.

      These structures are of vital importance because they are the ones that allow the detection of temperature variations, taking in particular the temperature of the body itself as a reference, thus establishing whether the environment is colder or warmer and how pleasant it is. They are also able to detect mechanical deformation of the skin, although this function is more typical of other mechanoreceptors, as is the case with Pacini’s corpuscles.

      In fact, they differ from this other type of skin receptor in that the Ruffini’s corpuscles adapt slowly. That means they are able to detect sustained stimuli on the skin, In addition to the light stretches that can be exerted on this fabric.

      It should be noted that not only are they able to detect stretching, but also perceive the joint angle, the speed of the mechanical stimulus on the skin and the type of stretch.

      General aspects of mechanoreceptors

      In the sense of touch, they play a leading role up to four different types of mechanoreceptors. One of them is the Ruffini corpuscle, in addition to those of Pacini, Merkel and Meissner.

      What they all have in common is that they are in the skin and respond to physical changes that can occur in this tissue. They act as systems of signal transducers, converting mechanical stimulation into electrochemical stimulation, being sent to the central nervous system so that they can organize a response if needed.

      Signals are sent in the form of bursts of nervous bursts, And depending on the characteristics of the sensory cell itself such as the type of stimulus for which it is responsible, the stimulation will continue or, on the contrary, gradually diminish.

      These cell types have been classified according to their behavior during two phases: dynamic and static. Dynamic phase refers to when the intensity of the stimulus changes, for example, when heat is applied and has ceased to be applied to the skin. Instead, it is understood as the static phase when the stimulus does not change its stimulation intensity on the organism.

      Receptors that are only stimulated during the dynamic phase have been named rapidly adapting or phasic mechanoreceptors, And this is the case of the Pacini corpuscles.

      On the other hand, those which are stimulated during the dynamic and static phases are known as the slow-adapting mechanoreceptors, Being the case of those of Ruffini.

      On another side, there is a second classification, Depending on the size of the area in which these types of receivers are charging. Type I receptors are those that receive signals or are responsible for stimulating small receptive fields, while type II receptors are responsible for larger receptive fields.

      Bibliographical references:

      • Halata, Z. (1988). Chapter 24. The Ruffini corpuscle is a receptor for stretching the connective tissue of the skin and the musculoskeletal system. Transduction and Cellular Mechanisms in Sensory Receptors, 221-229.
      • Paré M., Behets C., Cornu O. (2003). Possession of suspected rufinite corpuscles in said human index. The Journal of Comparative Neurology; 456: 260-266.

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