. Cytology. Cytology. a relational coil. If they are virtually single, then to become relationally coiled requires only that the potentially double strand twist on its own axis. This theory does, however, fail to explain two occasionally re- ported observations, namely, the development of a minor coil at right angles to the major coil and the relational coiling of homologous chromo- somes at zygotene. The former, however, is at the limit of optical reso-. Figure 7-3. Photomicrograph of Late Diakinesis Chromosome of Trillium erectum with a Schematic Representation of Four-strand Paranemic-Plec-
. Cytology. Cytology. a relational coil. If they are virtually single, then to become relationally coiled requires only that the potentially double strand twist on its own axis. This theory does, however, fail to explain two occasionally re- ported observations, namely, the development of a minor coil at right angles to the major coil and the relational coiling of homologous chromo- somes at zygotene. The former, however, is at the limit of optical reso-. Figure 7-3. Photomicrograph of Late Diakinesis Chromosome of Trillium erectum with a Schematic Representation of Four-strand Paranemic-Plec- tonemic Association in a Half-Bivalent. Each strand in the diagram is a half chromatid. (From Wilson, G. B., Sparrow, A. H., and Pond, V., 1959. "Sub- Chromatid Rearrangements in Trillium erectum. I. Origin and Nature of Configurations Induced by Ionizing Radiation," Am. J. Botany, 46, Fig. 1, p. 310. Courtesy of Dr. A. H. Sparrow, Brookhaven National Laboratory.) lution and is considered by many to be either an optical illusion or a zigzag which would be expected in a longitudinally heterogeneous thread. With respect to the latter observation, there is no indisputable evidence that such relational coiling actually exists, since the few cases illustrated seem equally likely to be accidental overlaps. The electron microscope has so far added little to our knowledge of chromosome geometry beyond indicating that component strands are almost certainly made up of many (probably 64) microfibrils which are THE CHROMOSOME COILING CYCLE / 169. 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
Size: 1711px × 1460px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
