Upon bright illumination, pigment granules in the photoreceptors of the fly compound eye migrate transversely toward the rhabdomeres (Kirschfeld & Franceschini, 1969). The granules absorb light passing down the rhabdomeric light guide, thereby reducing the light available to the visual pigment. This light-regulating mechanism is found in a number of invertebrate eyes (Stavenga, 1979) and has be...

Calcium has been implicated in the regulation of many cellular motility events. In this study we have examined the role of different Ca2+ concentrations on the in vitro transport of pigment within cultured chromatophores. Cells treated with Brij detergent for 1-2 min were stripped of their plasma membranes, leaving their cytoskeleton and associated pigment granules exposed to the external milie...

The folded cortex of the growing oocyte of the frog extends as microvilli into the substance of the developing vitelline membrane and, internal to the folds, possesses a layer of cortical granules. Free ribosomes, smooth-walled vesicles, coated vesicles, tubules, and electron-opaque granules are abundant in the peripheral zone of the cortex. Mitochondria, lipochondria, pigment granules, and ele...

Benzidine dihydrochloride in the presence of dimethylsulfoxide reacts with myeloperoxidase contained within the granules of polymorphonuclear leukocytes obtained from the oral cavity. A blue meriquinoid oxidation product is formed in the presence of hydrogen peroxide, which can be extracted from the granules with a combination of methyl alcohol and dimethylsulfoxide. A stable yellow-brown pigme...

A study was made of the diffusion of the red pigment echinochrome from the eggs of the sea urchin, Arbacia punctulata, into sea water. Unfertilized eggs retained their pigment, over periods of hours. Outward diffusion of pigment from unfertilized eggs normally is entirely negligible, or does not occur at all. Enchancing the calcium or potassium content of the artificial sea water (while retaini...

One of the most attractive characteristics of a horse testis is the change of the weight during development. As the testicular weight changes and the number of Leydig cells decreases, pigments appear in interstitial tissues. In the present study, the characteristics of the pigments found in the interstitial tissues were examined histochemically and ultrastructurally. Specific stainings indicate...

The test cell in the ovary of the tunicate Styela contains a large and robust Golgi complex which demonstrates a regional structural differentiation. In one of the regions, branching of the lamellae occurs resulting in a honeycomb or lattice-type arrangement. Small, dense granules or homogeneous material of moderate density may be present within certain of the Golgi cisternae. The close associa...

The mouse pigment mutant pale ear, ep/ep, which has a defect in kidney lysosomal enzyme secretion, had prolonged bleeding on experimental injury. Platelet counts and platelet protein did not differ from normal. There was, however, a deficiency in the platelet dense granule contents, serotonin, ATP, and ADP. Furthermore, a marked reduction of platelet dense granules was observed by electron micr...