2018 Group Project 3
| Projects 2018: 1 Adrenal Medulla | 3 Melanocytes | 4 Cardiac | 5 Dorsal Root Ganglion |
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Melanocytes
Introduction
History
Tissue Organ Structure and Function
Skin
Ears
Melanocytes are mainly present in the cochlea, vestibular organ and endolymphatic sac:
In the cochlea of humans, melanocytes are found in the vascularised epithelial tissue in the intermediate layer of the stria vascularis and the modiolus, between the marginal and basal cell layers [1]. During development, marginal layer cuboidal epithelium develops processes which interdigitate with the intermediate melanocytes and basal cells [2]. Based on studies performed on mice models, it is thought that melanocytes are important for the development of the endocochlear potential (EP), produced by strial cells (Figure 1). Intermediate melanocytes conduct K+, which plays an important role in sound conductance, as it flows from the endolymph into the ciliated epithelial cells of the ear via mechano-electrical channels. This influx of K+ is driven by a combination of the membrane potential of these ciliated epithelial cells, and the EP. A study on guinea pig models showed that blocking the K+ channels of melanocytes produces a lower EP [3]. This study agrees with evidence showing that mice deficient in cochlea melanocytes have a lower EP, requiring a greater sound stimulus to produce an action potential [4].
Figure 1: The cochlea of a Wv/Wv mutant showing the distribution of pigment within the Stria Vascularis [5]
Eyes
The uveal tract (iris, ciliary body and choroid) and conjunctiva normally contains melanocytes derived from the neuro-ectodermal neural crest. Peri-orbital soft tissue is also derived from the embryonic neural crest.[6] On the other hand, pigmented melanocytes (such as those found on the retina) were derived from the neuroepithelium or from different layers of the optic cup. [7] Eye melanocytes (like all other melanocytes) differentiate into melanin-producing cells, which in this case determines a person's eye colour, protect the eye from UV radiation [8] and many ocular diseases that can cause blindness, including age-related macular degeneration. [9] Melanocytes found in the eye are not able to participate in regeneration unlike epidermal melanocytes. [10]
Heart
Figure 3.
A differential interference contrast (DIC) microscopical image of a cardiac melanocyte present in an isolated atrial cell of an embryonic mouse pup. The white arrow indicates the cardiac melanocyte that is found amidst the atrial myocytes that are marked by the yellow arrowheads. [11]
Central Nervous System
Melanocytes can also be found within the Central Nervous System, primarily in the leptomeninges [12], which consists of the inner two layers membranes of the meninges, the pia mater and arachnoid, which encapsulate the brain and the spinal cord. While its function within the meninges is unknown, they are essential to the health of the meninges, with their removal increases the risk of aseptic meningitis [13]. Furthermore, due to its receptivity to the same signalling molecules as neurons, scientists can study diseases afflicting the central nervous system using it as a model [14].
Leptomeninges comprises the arachnoid and pia mater
Embryonic Origins
Development Time Course
Molecular Mechanisms/ Factors/ Genes
Animal Models
Current Research
Abnormalities
Glossary
References
- ↑ Meyer zum Gottesberge AM. (1988). Physiology and pathophysiology of inner ear melanin. Pigment Cell Res. , 1, 238-49. PMID: 3070525
- ↑ Steel KP & Barkway C. (1989). Another role for melanocytes: their importance for normal stria vascularis development in the mammalian inner ear. Development , 107, 453-63. PMID: 2612372
- ↑ Takeuchi S, Kakigi A, Takeda T, Saito H & Irimajiri A. (1996). Intravascularly applied K(+)-channel blockers suppress differently the positive endocochlear potential maintained by vascular perfusion. Hear. Res. , 101, 181-5. PMID: 8951443
- ↑ Cable J, Huszar D, Jaenisch R & Steel KP. (1994). Effects of mutations at the W locus (c-kit) on inner ear pigmentation and function in the mouse. Pigment Cell Res. , 7, 17-32. PMID: 7521050
- ↑ DENIER A. (1951). [Microwaves of 12 cm; their biological and therapeutic effect]. J Radiol Electrol Arch Electr Medicale , 32, 664-5. PMID: 14909014
- ↑ Schoenfield L. (2014). Uveal melanoma: A pathologist's perspective and review of translational developments. Adv Anat Pathol , 21, 138-43. PMID: 24508696 DOI.
- ↑ Baderca F, Solovan C & Boghian L. (2013). Epidemiological and morphological data of ocular melanocytic lesions. Rom J Morphol Embryol , 54, 77-83. PMID: 23529312
- ↑ Hou L & Pavan WJ. (2008). Transcriptional and signaling regulation in neural crest stem cell-derived melanocyte development: do all roads lead to Mitf?. Cell Res. , 18, 1163-76. PMID: 19002157 DOI.
- ↑ Hu DN, Simon JD & Sarna T. (2008). Role of ocular melanin in ophthalmic physiology and pathology. Photochem. Photobiol. , 84, 639-44. PMID: 18346089 DOI.
- ↑ Yamaguchi Y & Hearing VJ. (2014). Melanocytes and their diseases. Cold Spring Harb Perspect Med , 4, . PMID: 24789876 DOI.
- ↑ Hwang H, Liu F, Levin MD & Patel VV. (2014). Isolating primary melanocyte-like cells from the mouse heart. J Vis Exp , , 4357. PMID: 25285608 DOI.
- ↑ Gudjohnsen SA, Atacho DA, Gesbert F, Raposo G, Hurbain I, Larue L, Steingrimsson E & Petersen PH. (2015). Meningeal Melanocytes in the Mouse: Distribution and Dependence on Mitf. Front Neuroanat , 9, 149. PMID: 26635543 DOI.
- ↑ Goldgeier MH, Klein LE, Klein-Angerer S, Moellmann G & Nordlund JJ. (1984). The distribution of melanocytes in the leptomeninges of the human brain. J. Invest. Dermatol. , 82, 235-8. PMID: 6699426
- ↑ Yaar M & Park HY. (2012). Melanocytes: a window into the nervous system. J. Invest. Dermatol. , 132, 835-45. PMID: 22158549 DOI.
