Metaphase II

The main features of metaphase II are as follows: (1) The centromeres of the chromosomes become aligned along the equator. (2) New spindles become conspicuous and complete.

The two spindles may be formed either perpendicular to the ones that had formed in metaphase I or along the same plane. A spindle fiber is attached to each centromere, and other spindle fibers extend in arcs from pole to pole (see Figs. 12.2 and 12.4G).

Chapter 12

A. Early Prophase I. Chromosomes begin to coil and contract and appear as threads.

B. Prophase I. Homologous chromosomes become aligned in pairs, and some crossing-over is visible.

C. Metaphase I. Bivalents become aligned along the equator.

D. Anaphase I. Homologous chromosomes separate and migrate to opposite poles.

E. Late Telophase I. Chromosomes are at the poles, and the original cell becomes two cells.

Phases Meiosis PhotomicrgraphHomogolous Chromosomes Photomicrogrpah

Figure 12.4 Various phases of meiosis in crested wheat grass. (Photomicrographs by William Tai)

Homogolous Chromosomes Photomicrogrpah

Figure 12.4 Various phases of meiosis in crested wheat grass. (Photomicrographs by William Tai)

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Essentials of Human Physiology

Essentials of Human Physiology

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