Black-white vision

Light-absorbing pigments differentiate rod cells for black-white vision and three types of cone cells for color vision 807... 

The staining of germinated pollen of Hippeastrum hybridum with colchicine demonstrates green-yellow emission of microtubules (better vision in black-white image) around nuclei of pollen grain (threads at the division of the nucleus) and spermium on the tip of the pollen tube, where spermium moves, as well as in some bridge sites of the tube (Fig. 10). The similar fluorescent allelochemicals may be also used as fluorescent dyes at the cellular diagnostics (Roshchina, 2005 b). 

Vitamin A helps maintain the skin and mucous membranes of the oral cavity and the digestive, respiratory, reproductive, and urinary tracts. Vitamin A is also critical for vision. The aldehyde form of Vitamin A, called retinal, binds to a protein called opsin to form the visual pigment rhodopsin. This pigment is found in the rod cells of the retina of the eye. These cells are responsible for black-and-white vision. As you might expect, a deficiency of vitamin A can have terrible consequences. In children, lack of vitamin A leads to xerophthalmia, an eye disease that results first in night blindness and eventually in total blindness. The disease can be prevented by an adequate dietary or supplementary supply of this vitamin. Because vitamin A is stored in the liver, a dose of 0.03 mg will protect a child for six months. Yet in countries that have suffered from cruel famines, even this amount of vitamin A is unavailable, and the burdens of malnutrition and disease lead to total blindness in thousands of children. 

Closed-circuit television (CCTV) systems magnify print and small objects up to 60 times, with higher effective magnifications possible by close viewing. Users with vision as poor as 1/400 (20/8000) may be able to read ordinary print with CCTV [Fonda, 1981]. Some recent units are portable and contain black/white image reversal and contrast enhancement features. 

One of the first effects exhibited by hypoxia is loss of night vision. There are two kinds of receptor cells in the retina of the eye. One type, cones, senses color. The other type, rods, senses light, black and white vision. Rods are most... 

The human eye evolved to see not only different intensities of light (black-and-white vision) but different colors as well. The colors that we see depend on the interaction of light with the molecules or atoms within the thing we are looking at (7.3). 

Figure F5.1.9 Hering s theory of color vision stated color is due to three pairs of opposing codes. Figure courtesy of GretagMacbeth. This black and white facsimile of the figure is intended only as a placeholder for full-color version of figure go to http //www.currentprotocols.com/colorfigures...

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