Chromatophores (cell)

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Chromatophores in the skin of an East Pacific squid of the species Loligo opalescens .

As a chromatophore (from ancient Greek χρωμάτιον chromate , German , Pigment ' and ancient Greek φορός Phoros , German , carrying' ), also pigment cell or color cell is described in Biology a pigmented cell of tissue animals referred to, which is usually close to the surface in the body.

Many organisms also develop patterns of different colors on their surfaces. In many animals, this is due to cells in the tissue near the surface under the cuticle , calcareous shell or chitin shell or to the distribution of special pigment cells in their skin .

Some of these chromatophores can pass on their pigment, e.g. B. to other keratin- forming cells of the skin, so that it also appears in skin appendages such as scales , hair or feathers . Their colored effect is not only caused by the selective light absorption of the chromophore by pigments , but also arises as a so-called structural color through reflection , scattering and refraction on fine, often multilayered structures, especially with iridescent effects.

Types of chromatophores

A chromatophore as a pigment-containing cell in vertebrates , crustaceans , snails and cephalopods can be typed according to the type of pigment:

carries melanins ; brownish to black, e.g. B. in goblins or humans ( melanocytes )
Xanthophores and erythrophors
contains carotenoids and pterins; with a yellow-red color, as in chameleons
Guanophores or iridophores
stores reflective guanine crystals ; whitish-silvery-iridescent, in chameleons or neon tetras

The iridescence , a rainbow-colored shimmer in interference colors , comes about through refraction and reflection on multilayered structures in the cell. Iridophores from neon tetra can influence this effect by changing the distance between the layers containing guanine crystals and regulate it depending on the incidence of light.

Color change

A morphological color change occurs over a longer period of time - for example, depending on age or season. It is achieved by changing the amount of pigment in the individual color cells or by changing the total number of pigment cells.

In contrast to this, a physiological color change takes place quickly, through a change in the shape of the pigment cell or through a shift in the pigments it contains. This can happen depending on the situation to various stimuli, and some squid - both zehnarmigen as cuttlefish and squid as well as eight-armed like octopus - very quickly.

Color cells from plants

Plants also form pigments in cells of the epidermis of leaf or flower or fruit shell . In addition to chloroplasts , their color cells can contain, for example, chromoplasts with pigments that are then not used for photosynthesis . Their play of colors often represents attractive signals, not only for pollinating insects, but also for other animals that consume fruit and thus spread seeds . These organelles located within plant cells, the pigment-containing plastids , are summarized in botany using an older (outdated) collective term and also called "chromatophores".

See also

Individual evidence

  1. S. Yoshioka, B. Matsuhana, S. Tanaka, Y. Inouye, N. Oshima, S. Kinoshita: Mechanism of variable structural color in the neon tetra: quantitative evaluation of the Venetian blind model. In: JR Soc Interface. Volume 8, January 2001, pp. 56-66, doi: 10.1098 / rsif.2010.0253 , PMC 3024824 (free full text).
  2. ^ J. Clothier and J. Lythgoe: Light-induced color changes by the iridophores of the Neon tetra (Paracheirodon innesi). (Full text, English) In: Journal of Cell Science. Volume 88, 1987, pp. 663-668, PMID 3503061 .
  3. Entry on chromatophores. In: Römpp Online . Georg Thieme Verlag, accessed April 10, 2011.