1. In the cytoplasm of oocytes of stage Y(0), prior to the appearance of yolk, one observes a few scattered profiles of endoplasmic reticulum and numerous filamentous mitochondria, usually distributed at random but sometimes clustered. As the nuclear membrane begins to bulge outward, small granules and short rods appear in the perinuclear cytoplasm and endoplasmic reticulum becomes more promine...

The Holocentrus erythrophore, a red pigment cell, represents a model system for the study of organized intracellular transport. We have investigated the possibility that microtubules and actin are integral components of the pigment translocating motility machine. By creating cells that have total or partial loss of the microtubule framework we have demonstrated that the presence of microtubules...

I read, with keen interest, the CMAJ article “Tattoo reactions as a sign of sarcoidosis,” which described granulomatous tattoo reaction in a patient with systemic sarcoidosis. Tattoo sarcoidosis has been known for more than half a century, although only a few cases have been described. One hypothesis is that this may be a “pigment-induced disease.” Tattoo pigments may provide chronic antigenic ...

The full primary structure of a long-wavelength absorbing visual pigment of the small white butterfly, Pieris rapae crucivora, was determined by molecular cloning. In situ hybridization of the opsin mRNA of the novel visual pigment (PrL) demonstrated that it is expressed in the two distal photoreceptor cells (R3 and R4) as well as in the proximal photoreceptors (R5-8) in all three types of omma...

Melanophores are pigment cells found in the skin of lower vertebrates. The brownish-black pigment melanin is stored in organelles called melanosomes. In response to different stimuli, the cells can redistribute the melanosomes, and thereby change colour. During melanosome aggregation, a height increase has been observed in fish and frog melanophores across the cell centre. The mechanism by whic...

HERE is considerable reason to believe that the coat-color genes of mamT mals provide particularly favorable material for the study of the physiology of gene action, as the chain of reactions between gene and final character must be short relative to that in most internal and embryologically determined characteristics (E. S. RUSSELL 1946). Therefore a histological analysis of the pigments found...

Previous studies have shown that pigment granule dispersion and aggregation in melanophores of the African cichlid, Tilapia mossambica, are regulated by protein phosphorylation and dephosphorylation, respectively (Rozdzial, M. M., and L. T. Haimo. 1986. Cell. 47:1061-1070). The present studies suggest that calcineurin, a Ca2+/calmodulin-stimulated phosphatase, is the endogenous phosphatase that...

The emission properties of ocular lipofuscin granules isolated from human retinal pigment epithelial cells are examined by using steady-state fluorescence spectroscopy and spectrally resolved confocal microscopy. The shape of the emission spectrum of a thick sample of lipofuscin granules dried on glass varies with excitation energy. The polarization of this emission is wavelength-dependent, exh...

A 58-year-old Japanese man presented with a lesion on his left forearm; a black-grey macule 4 mm in diameter that had appeared in his childhood (Fig. 1a). He worked in an office and had no history of trauma at the site of the lesion. BN and basal cell carcinoma was suspected macroscopically. On dermoscopy, however, there was a pigment network-like structure consisting of randomly arranged, blac...