. Cytology. Cytology. Figure 5-1. Diagrammatic Representation of the Stages of Mitosis: (a) prophase; (b) metaphase; (c) anaphase; and (d) telophase. (From Wilson, G. B., 1952. "Outline of Genetics," Michigan State University Press, East Lansing, Mich., Fig. 2, p. 6.) The nucleus at this stage is as described in Chapter 4. The chromo- somes lie in the form of more or less loosely coiled threads, usually somewhat closely appressed to the membrane. Most cytologists consider them to be already duplicated, and some workers believe them to be multipartite. They may or may not stain intens
. Cytology. Cytology. Figure 5-1. Diagrammatic Representation of the Stages of Mitosis: (a) prophase; (b) metaphase; (c) anaphase; and (d) telophase. (From Wilson, G. B., 1952. "Outline of Genetics," Michigan State University Press, East Lansing, Mich., Fig. 2, p. 6.) The nucleus at this stage is as described in Chapter 4. The chromo- somes lie in the form of more or less loosely coiled threads, usually somewhat closely appressed to the membrane. Most cytologists consider them to be already duplicated, and some workers believe them to be multipartite. They may or may not stain intensely with standard nuclear stains at this stage, presumably depending on the distribution of nucleo- protein which appears to vary with the species. Nucleoli and Feulgen- positive chromocenters are also conspicuous during this stage. Prophase At the beginning of division the chromosomes start to contract, thicken, and undo their coiling. Part of this change appears to be asso- ciated with the development, at right angles to the old coil, of a new one which grows from a coil of many small gyres to one of relatively few larger ones. This coiling is generally obscured by the development of matrical material. Total end-to-end contraction is to approximately one-fifth the initial length (Sparrow, et ah, 1941). About midway through this process, it becomes obvious that each chromosome is at 120 / CHAPTER 5. 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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