. Cytology. Cytology. (a) (b) Figure 6-2. (a) First Maturation Division Spindle in Living Oocyte of Chaetopterus pergamentaceous Photographed with Polarization Optics. The bright chromosomal and continuous fibers of the spindle and the dark astral rays are all positively birefrigent and appear as dark bodies at the equator of the cell, (lb) Tracing of First Maturation Division Spindle of Chaetopterus Showing Detail of Component Parts. (From Inoue, S., 1953. "Polarization Optical Studies of the Mitotic Spindle. I. The Demonstration of Spindle Fibers in Living Cells," Chromosoma, 5, Fi


. Cytology. Cytology. (a) (b) Figure 6-2. (a) First Maturation Division Spindle in Living Oocyte of Chaetopterus pergamentaceous Photographed with Polarization Optics. The bright chromosomal and continuous fibers of the spindle and the dark astral rays are all positively birefrigent and appear as dark bodies at the equator of the cell, (lb) Tracing of First Maturation Division Spindle of Chaetopterus Showing Detail of Component Parts. (From Inoue, S., 1953. "Polarization Optical Studies of the Mitotic Spindle. I. The Demonstration of Spindle Fibers in Living Cells," Chromosoma, 5, Figs. 2 and 3, p. 490.) divides during the early part of mitosis. The products of division migrate until they take up positions opposite each other with the nucleus be- tween them. The so-called astral rays normally develop during the time of this migration. What connection these bodies have in the formation of the functional spindle is by no means clear despite many years of study. Proponents of the many versions of the centrosomal theory of spindle organization have been somewhat embarrassed by the finding that no such apparatus can be located in the cells of higher plants and that, furthermore, its existence is doubtful in many animal cells. In plant cells generally, and in many animal cells where there is no ap- parent centrosomal apparatus, no organized spindle is obvious until MECHANICS AND PHYSIOLOGY OF CELL DIVISION / 141. 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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