Sensory - Touch Development: Difference between revisions
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* '''A Cascade of Wnt, Eda, and Shh Signaling Is Essential for Touch Dome Merkel Cell Development'''<ref name=PMID27414798><pubmed>27414798</pubmed></ref> "In the skin, touch domes develop in tandem with primary hair follicles and contain sensory Merkel cells. We found dermal Wnt signaling and subsequent epidermal Eda/Edar signaling promoted Merkel cell morphogenesis by inducing Shh expression in early follicles. Lineage-specific gene deletions revealed intraepithelial Shh signaling was necessary for Merkel cell specification. Additionally, a Shh signaling agonist was sufficient to rescue Merkel cell differentiation in Edar-deficient skin. ...Although developmentally associated with hair follicles, fate mapping demonstrated Merkel cells primarily originated outside the hair follicle lineage. These findings suggest that touch dome development requires Wnt-dependent mesenchymal signals to establish reciprocal signaling within the developing ectoderm, including Eda signaling to primary hair placodes and ultimately Shh signaling from primary follicles to extrafollicular Merkel cell progenitors." | * '''A Cascade of Wnt, Eda, and Shh Signaling Is Essential for Touch Dome Merkel Cell Development'''<ref name=PMID27414798><pubmed>27414798</pubmed></ref> "In the skin, touch domes develop in tandem with primary hair follicles and contain sensory Merkel cells. We found dermal Wnt signaling and subsequent epidermal Eda/Edar signaling promoted Merkel cell morphogenesis by inducing Shh expression in early follicles. Lineage-specific gene deletions revealed intraepithelial Shh signaling was necessary for Merkel cell specification. Additionally, a Shh signaling agonist was sufficient to rescue Merkel cell differentiation in Edar-deficient skin. ...Although developmentally associated with hair follicles, fate mapping demonstrated Merkel cells primarily originated outside the hair follicle lineage. These findings suggest that touch dome development requires Wnt-dependent mesenchymal signals to establish reciprocal signaling within the developing ectoderm, including Eda signaling to primary hair placodes and ultimately Shh signaling from primary follicles to extrafollicular Merkel cell progenitors." [[Developmental Signals - Sonic hedgehog|Sonic hedgehog]] | ||
* '''Unipotent, Atoh1+ progenitors maintain the Merkel cell population in embryonic and adult mice'''<ref name=PMID25624394><pubmed>25624394</pubmed>| [http://jcb.rupress.org/content/208/3/367.long J Cell Biol.]</ref> "Resident progenitor cells in mammalian skin generate new cells as a part of tissue homeostasis. We sought to identify the progenitors of Merkel cells, a unique skin cell type that plays critical roles in mechanosensation. We found that some Atoh1-expressing cells in the hairy skin and whisker follicles are mitotically active at embryonic and postnatal ages. Genetic fate-mapping revealed that these Atoh1-expressing cells give rise solely to Merkel cells. Furthermore, selective ablation of Atoh1(+) skin cells in adult mice led to a permanent reduction in Merkel cell numbers, demonstrating that other stem cell populations are incapable of producing Merkel cells. These data identify a novel, unipotent progenitor population in the skin that gives rise to Merkel cells both during development and adulthood." | * '''Unipotent, Atoh1+ progenitors maintain the Merkel cell population in embryonic and adult mice'''<ref name=PMID25624394><pubmed>25624394</pubmed>| [http://jcb.rupress.org/content/208/3/367.long J Cell Biol.]</ref> "Resident progenitor cells in mammalian skin generate new cells as a part of tissue homeostasis. We sought to identify the progenitors of Merkel cells, a unique skin cell type that plays critical roles in mechanosensation. We found that some Atoh1-expressing cells in the hairy skin and whisker follicles are mitotically active at embryonic and postnatal ages. Genetic fate-mapping revealed that these Atoh1-expressing cells give rise solely to Merkel cells. Furthermore, selective ablation of Atoh1(+) skin cells in adult mice led to a permanent reduction in Merkel cell numbers, demonstrating that other stem cell populations are incapable of producing Merkel cells. These data identify a novel, unipotent progenitor population in the skin that gives rise to Merkel cells both during development and adulthood." | ||
* '''Embryonic maturation of epidermal Merkel cells is controlled by a redundant transcription factor network'''<ref name=PMID25468937><pubmed>25468937</pubmed></ref> Merkel cell-neurite complexes are located in touch-sensitive areas of the mammalian skin and are involved in recognition of the texture and shape of objects. Merkel cells are essential for these tactile discriminations, as they generate action potentials in response to touch stimuli and induce the firing of innervating afferent nerves. It has been shown that Merkel cells originate from epidermal stem cells, but the cellular and molecular mechanisms of their development are largely unknown. In this study, we analyzed Merkel cell differentiation during development and found that it is a temporally regulated maturation process characterized by a sequential activation of Merkel cell-specific genes. We uncovered key transcription factors controlling this process and showed that the transcription factor Atoh1 is required for initial Merkel cell specification. The subsequent maturation steps of Merkel cell differentiation are controlled by cooperative function of the transcription factors Sox2 and Isl1, which physically interact and work to sustain Atoh1 expression" | * '''Embryonic maturation of epidermal Merkel cells is controlled by a redundant transcription factor network'''<ref name=PMID25468937><pubmed>25468937</pubmed></ref> Merkel cell-neurite complexes are located in touch-sensitive areas of the mammalian skin and are involved in recognition of the texture and shape of objects. Merkel cells are essential for these tactile discriminations, as they generate action potentials in response to touch stimuli and induce the firing of innervating afferent nerves. It has been shown that Merkel cells originate from epidermal stem cells, but the cellular and molecular mechanisms of their development are largely unknown. In this study, we analyzed Merkel cell differentiation during development and found that it is a temporally regulated maturation process characterized by a sequential activation of Merkel cell-specific genes. We uncovered key transcription factors controlling this process and showed that the transcription factor Atoh1 is required for initial Merkel cell specification. The subsequent maturation steps of Merkel cell differentiation are controlled by cooperative function of the transcription factors Sox2 and Isl1, which physically interact and work to sustain Atoh1 expression" |
Revision as of 09:45, 22 September 2016
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Introduction
These notes introduce the development of the sense of touch, part of the somatosensory system. Because of the distribution of the sensory structures within the skin, this topic is generally also covered in integumentary development.
Senses Links: Introduction | placode | Hearing and Balance hearing | balance | vision | smell | taste | touch | Stage 22 | Category:Sensory |
Some Recent Findings
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More recent papers |
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Touch Development <pubmed limit=5>Touch Development</pubmed> |
Historic People
- Georg Meissner - (1829-1905) German histologist, physiologist and anatomist. Beiträge zur Anatomie und Physiologie der Haut. (Contributions to the anatomy and physiology of the skin.) Leipzig, 1853.
- Friedrich Sigmund Merkel- (1845-1919) German anatomist and histologist, the name "Merckel cell" was based upon his first full description of touch cells (Tastzellen) and named by Robert Bonnet (1851–1921). Referred to these cells as Tastzellen or "touch cells" but this proposed function has been controversial as it has been hard to prove.
- Filippo Pacini - (1812-1883) Italian anatomist, published in 1840, and the name "Pacini's corpuscles" was proposed in 1844 by Henle and also by Kölliker.
- Angelo Ruffini (1864-1929) Italian histologist and embryologist, the name "Ruffini corpuscles" was based upon his first description of skin mechanoreceptors.
Touch Receptors
Touch receptors in mammalian skin and the neural encoding of reception.[8]
Touch Pathway
Pacinian corpuscle
These receptors are lamellar vibration receptors that produce rapidly adapting responses. They are located in the subcutaneous tissue, deeper in interosseous membranes, and also mesenteries of the gut. The inner core cells form from Schwann cells extending from the nerve terminal.
Meissner's corpuscle
Located in glabrous skin the mechanoreceptor lies between the dermal papillae for sensitivity to light touch. They are rapidly adaptive elongated receptors formed by a connective tissue capsule that formed by several lamellae of Schwann cells enclosing one or more afferent nerve fibres.
Meissner's corpuscles are located throughout the skin and are seen concentrated in regions of high touch (finger tips, lips, genital regions).
Merkel cell
Merkel cell complexes mediate slowly adapting type I (SAI) responses, which are characterized by an irregular firing pattern during sustained pressure.
Merkel cells arise in the embryo[4] and in the adult[3] from an epidermal progenitor cell population. These cells express the transcription factor Atoh1 and when differentiated are post-mitotic.
Isolated Merkel cell (em) |
Merkel cell (Merkel-Ranvier cell) integumentary (skin) receptor cell connected with somatosensory afferents.
Cell characteristics a polylobulated nucleus and numerous typical dense-core granules in a clear cytoplasm. The name "Merckel cell" was based upon Friedrich Sigmund Merkel (1845 – 1919) a German anatomist and histologist, first description of these touch cells (Tastzellen) and named in his honour by Robert Bonnet (1851–1921). Scale bar 5 µm (Stain - Osmium) |
In the adult, abnormalities in Merkel cell development can lead to the rare disease of Merkel cell carcinoma (MCC).
Sensory Modalities
Thermoreceptors
- Receptors for heat (warmth) and cold (chill) detection.
- heat - C-fibres
- cold - Aδ fibres
Nociceptors
- Receptors for encoding and processing noxious stimuli.
- A-δ nociceptors
- Polymodal C-nociceptors
- C- mechano-insensitive nociceptors
Abnormalities
- Merkel cell carcinoma (MCC) PMID 12007193
References
- ↑ <pubmed>20956378</pubmed>| PMC2958478 | JCB
- ↑ <pubmed>27414798</pubmed>
- ↑ 3.0 3.1 <pubmed>25624394</pubmed>| J Cell Biol.
- ↑ 4.0 4.1 <pubmed>25468937</pubmed>
- ↑ <pubmed>22710006</pubmed>
- ↑ <pubmed>21906948</pubmed>
- ↑ <pubmed>21041368</pubmed>
- ↑ <pubmed>20956378</pubmed>| PMC2958478 | JCB
Reviews
<pubmed>25480024</pubmed> <pubmed>25414303</pubmed> <pubmed>21841076</pubmed> <pubmed>20956378</pubmed>| JCB
Articles
<pubmed>25471886</pubmed>
Books
Neurobiology of Sensation and Reward. Gottfried JA, editor. Boca Raton (FL): CRC Press; 2011. Chapter 7 - Touch PMID 22593916
Search PubMed
Search Pubmed: Touch Development | touch receptors |
External Links
External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.
- Merkel cell carcinoma - http://www.merkelcell.org
Terms
- free nerve endings- abundantly innervate the epidermis, include nociceptors and low-threshold C-fibers.
- glabrous - smooth hairless skin for example the fingertips, palms, and soles.
- lanceolate endings - rapidly adapting or down hair afferents sensitive light-touch receptors that depend on Neurotrophin-4 for proper development.
- Meissner’s corpuscles - glabrous skin mechanoreceptor lie between the dermal papillae for sensitivity to light touch. They are rapidly adaptive elongated receptors formed by a connective tissue capsule that formed by several lamellae of Schwann cells enclosing one or more afferent nerve fibres.
- Merkel cells - (Merkel's disks, Merkel cell–neuron complexes) mediate slowly adapting type I (SAI) responses, which are characterized by an irregular firing pattern during sustained pressure.
- Pacinian corpuscles- lamellar vibration receptors that produce rapidly adapting responses.
- Ruffini endings - proposed to mediate stretch-sensitive slowly adapting type II (SAII) responses, unknown developmental pathwayreceptors.
Glossary Links
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Cite this page: Hill, M.A. (2024, May 3) Embryology Sensory - Touch Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Sensory_-_Touch_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G