The main features of metaphase I are as follows: (1) The chromosomes become aligned in pairs at the equator of the cell. (2) The now complete spindle becomes conspicuous (Figs. 12.2, 12.4C).
Metaphase I resembles metaphase of mitosis, except that when the chromosomes move to the invisible, circular, essentially platelike equator, the centromeres of the chromosomes are paired, with the homologous chromosomes lined up directly opposite one another on each side of the equator (Fig. 12.5). Also, at this stage, as in mitosis, each chromosome's two chromatids are held together at their centromeres and function as a single unit.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.