ISSN:
1432-0878
Keywords:
Pigment cell
;
Red hair
;
Sunburn
;
Man
;
Electron Microscopy
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary Pigment cells of human red hair (pheomelanocytes) are never connected to keratinocytes by desmosomes or other defined cell junctions. In the dendritic processes of pheomelanocytes, thin filaments, about 50–80 Å in diameter, and microtubuli can be observed. Early prepheomelanosomes contain loosely arranged filaments. With the onset of pheomelanogenesis dense material is deposited on the filaments. Distinction between late prepheomelanosomes and pheomelanosomes is not clearly possible, because of the disorganized appearance of the content. Furthermore, the content of pheomelanosomes sometimes seems to be disintegrated. By means of the DOPA reaction, tyrosinase activity is shown to be present in: a) prepheomelanosomes, b) large cisternae apposed at one side of dictyosomes, c) small cisternae of the smooth endoplasmic reticulum, and d) coated and uncoated vesicles. The results suggest that red pigment granules are formed in a manner similar to that of melanin granules. It is further assumed that an inadequate stability of pheomelanoprotein accounts for the inability of red-haired people to develop effective protection against ultraviolet light.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00222168
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