Meissner's corpuscle
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Meissner's corpuscles (discovered by the anatomist Georg Meissner (1829-1903) are a type of mechanoreceptor and more specifically, a tacticle corpuscle (corpusculum tactus). They are distributed throughout the skin, but concentrated in areas especially sensitive to light touch, such as the fingertips, palms, soles, lips, tongue, face, nipples and the external skin of the male and female genitals. They are primarily located just beneath the epidermis within the dermal papillae.
Meissner's corpuscles are encapsulated unmyelinated nerve endings, which consist of flattened supportive cells arranged as horizontal lamellae surrounded by a connective tissue capsule. A single nerve fiber meanders between the lamellae and throughout the corpuscle. Any physical deformation in the corpuscle will cause an action potential in the nerve. Since they are rapidly adapting or phasic, the action potentials generated quickly decrease and eventually cease. If the stimulus is removed, the corpuscle regains its shape and while doing so (ie: while physically reforming) causes another volley of action potentials to be generated. (This is the reason one stops "feeling" one's clothes.) Because of their superficial location in the dermis, 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. Feelings of deep pressure (from a poke, for instance) are generated from Pacinian corpuscles (the only other type of phasic tactile mechanoreceptor), which are located deeper in the dermis, and some free nerve endings. Also, Meissner's corpuscles do not detect pain; this is signalled exclusively by free nerve endings.
External links
- Photomicrograph of Meissner's corpuscles within the skin (http://medocs.ucdavis.edu/CHA/402/labsyl/99/12.htm) (see micrograph #3 on the page), part of the UC Davis online histology course.
- Donald L. Rubbelke D.A. Tissues of the Human Body: An Introduction. McGraw-Hill. 1999 Meissner's and Pacinian corpuscles (http://www.mhhe.com/biosci/ap/histology_mh/receptor.html#pacinian)
- Dawn A. Tamarkin, Ph.D. Anatomy and Physiology Unit 15 Vision and Somatic Senses: Touch and Pressure (http://distance.stcc.edu/AandP/AP/AP2pages/unit15/touch.htm)
- S Gilman. Joint position sense and vibration sense: anatomical organisation and assessment. (http://jnnp.bmjjournals.com/cgi/content/full/73/5/473) Journal of Neurology Neurosurgery and Psychiatry 2002;73:473-477