. Cytology. Cytology. ileum of the mosquito larva (Berger, 1938; Grell, 1946). In the latter case, diploidy is apparently restored by a series of mitoses without fur- ther chromosome duplication. Senescent tissues also appear to have many polytene nuclei. It is yet too early to assess the importance of this variation, but it does seem to offer a plasticity which may prove of con- siderable value in studies of Figure 8-3. Photomicrograph of Flattened Nucleus from the Late Milk Stage of Corn Endosperm Showing Multistranded (Polytene) Character of the Chromosomes. (From Duncan,
. Cytology. Cytology. ileum of the mosquito larva (Berger, 1938; Grell, 1946). In the latter case, diploidy is apparently restored by a series of mitoses without fur- ther chromosome duplication. Senescent tissues also appear to have many polytene nuclei. It is yet too early to assess the importance of this variation, but it does seem to offer a plasticity which may prove of con- siderable value in studies of Figure 8-3. Photomicrograph of Flattened Nucleus from the Late Milk Stage of Corn Endosperm Showing Multistranded (Polytene) Character of the Chromosomes. (From Duncan, R. E. and Ross, J. G., 1950. "The Nucleus in Differentiation and Development," J. Heredity, 41, Fig. 5, p. 261. Courtesy of Dr. Robert E. Duncan, Wisconsin Neurological Foundation, Madison, Wis.) CHANGES IN CHROMOSOME STRUCTURE In addition to changes in whole chromosome sets or parts thereof, alteration in the structure of individual chromosomes may occur spon- taneously or by induction. Such changes may result in quantitative altera- tions of genes (deletions and duphcations) or only in spatial rearrange- CYTOGENETICS / 181. 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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