melanosome

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melanosome

[mə′lan·ə‚sōm]
(cell and molecular biology)
An organelle which contains melanin and in which tyrosinase activity is not demonstrable.
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Even though we found that total melanin pigment concentration in rusty head plumage did not differ between the sexes, the structure and arrangement of the involved melanosomes may cause distinctive reflectance properties (McGraw et al.
13 ( ANI ): Researchers have found evidence for evolutionary shifts in the rules that govern the relationship between color and the shape of pigment-containing organelles known as melanosomes.
Color changes in teleosts are due to the aggregation/dispersion of pigment within the light-absorbing chromatophores, in particular to the motile activity of melanosomes, and to the reflecting changes in active iridophores (Beeching 1995, Fujii et al.
The tumour cell has a large, irregular nucleus and a prominent nucleolus, with heavily pigmented melanosomes (hematoxylin and eosin x200).
Melanosomes consist primarily of proteins that are synthesised in the endoplasmic reticulum (ER) and are then routed to the melanosome either directly or via the Golgi where additional modifications, such as glycosylation, are made to the protein.
Otherwise, our case closely resembled this "CCS-like gastrointestinal tumor," which is typically characterized as having a more sheetlike or pseudoalveolar or pseudopapillary growth pattern lacking macronucleoli and as lacking melanosomes.
In vitro tests show a decrease of the transformation of the phenylalanin in tyrosine, a decrease of the activity of the tyrosinase and a decrease of the transfer of melanosomes in keratinocytes.
UV radiation regulates melanogenesis directly by increasing tyrosinase expression and activity in melanocytes or indirectly through the release of keratinocyte-derived factor: this induces the subsequent accumulation of melanosomes in melanocytes.
Darker skin has more reactive melanocytes, or pigment-making cells, and has more and stronger melanosomes, which are small packets that contain skin pigment, both of which provide some inherent protection against UV rays but not enough," he said.
RCM provides great convenience in the assessment of normal skin and particularly in evaluating melanocytic lesions due to high contrast features of melanins and melanosomes.
The mechanism of color change may involve increased or decreased melanocyte release of melanosomes resulting from changes in MSH levels.
The goal of hyperpigmentation treatment includes the degrading of melanosomes, blocking the formation of melanosomes, and slowing the growth of melanocytes.