. Cytology. Cytology. 260-m// region of the ultraviolet spectrum makes possible the identifica- tion and measurement of these substances in cell structures such as the chromosomes and cytoplasm (Figure 11-18). The most serious drawback to use of the ultraviolet microscope is the lethal effect of ultraviolet radiation on living cells. The amount of radi- Cy toplasmic Nucleic acid % 5 Hemoglobin 10" fiq Phase. Stem cell Mature eel Figure 11-20. Graph Showing Changes in Cytoplasmic Composition Dur- ing Mammalian Red Blood Cell Formation as Measured by Ultraviolet Mi- crospectrophotometry. Sy
. Cytology. Cytology. 260-m// region of the ultraviolet spectrum makes possible the identifica- tion and measurement of these substances in cell structures such as the chromosomes and cytoplasm (Figure 11-18). The most serious drawback to use of the ultraviolet microscope is the lethal effect of ultraviolet radiation on living cells. The amount of radi- Cy toplasmic Nucleic acid % 5 Hemoglobin 10" fiq Phase. Stem cell Mature eel Figure 11-20. Graph Showing Changes in Cytoplasmic Composition Dur- ing Mammalian Red Blood Cell Formation as Measured by Ultraviolet Mi- crospectrophotometry. Synthesis of RNA associated with endocellular growth processes is completed before formation of the mature erythrocyte. The de- velopmental phase where the concentration of cytoplasmic RNA is virtually zero, represents the period during which intensive production of hemoglobin is initiated. Solid circles, per cent cytoplasmic RNA; line through open cir- cles, total amount of hemoglobin in cell; dotted line, total cellular protein. (From Thorell, B., 1947. "The Relation of Nucleic Acids to the Formation and DifTerentiation of Cellular Proteins," Cold Spring Harbor Symposia Quant. Biol., 12, Fig. 14, p. 253.) ation necessary to photograph cell structures with ultraviolet light is very close to doses which either kill or seriously damage the living cell. This disadvantage has been overcome somewhat by the use of more sensitive recording devices such as the quartz window television tube. While the advent of television electronics is quite recent in biology it has interesting possibilities for teaching and research. 240 / CHAPTER 11. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Wilson, G. B. (George Bernard), 1914-; Morrison, John H. (John Herbert), 1927-. New York, Reinhold
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