metaphase

metaphase

 [met´ah-fāz]

the second stage of cell division (mitosis or meiosis), in which the chromosomes, each consisting of two chromatids, are arranged in the equatorial plane of the spindle prior to separation.

met·a·phase

(met'ă-fās),

The stage of mitosis or meiosis in which the chromosomes become aligned on the equatorial plate of the cell separating the centromeres. In mitosis and in the second meiotic division, the centromeres of each chromosome divide and the two daughter centromeres are directed toward opposite poles of the cell; in the first division of meiosis, the centromeres do not divide but the centromeres of each pair of homologous chromosomes become directed toward opposite poles.

[meta- + G. phasis, an appearance]

metaphase

(mĕt′ə-fāz′)

n.

The stage of mitosis and meiosis, following prophase and preceding anaphase, during which the chromosomes are aligned along the metaphase plate.

metaphase

A stage in mitosis or meiosis during which the chromosomes align along the equatorial plate of the cell and kinetochores contact the microtubuli of the spindle apparatus. The chromosomes are most condensed and best studied by classic cytogenetics during metaphase.

met·a·phase

(met'ă-fāz)

The stage of mitosis or meiosis in which the chromosomes become aligned on the equatorial plate of the cell separating the centromeres. In mitosis and in the second meiotic division, the centromeres of each chromosome divide, and the two daughter centromeres are directed toward opposite poles of the cell; in the first division of meiosis, the centromeres do not divide, but the centromeres of each pair of homologous chromosomes become directed toward opposite poles.

[meta- + G. phasis, an appearance]

metaphase

Stage of MITOSIS or MEIOSIS during which the chromosomes are aligned around the equator of the cell and are visible on microscopy. The stage at which the banding pattern of the chromosomes is apparent.

Fig. 220 Metaphase . Position of chromosomes in mitosis and meiosis.

metaphase

a stage of nuclear division in EUKARYOTE cells, occurring once in MITOSIS and twice in MEIOSIS. The main process involved is the organization of CHROMOSOMES at the equator of a spindle, forming a metaphase plate. Each chromosome is divided into two CHROMATIDS, joined at a CENTROMERE. The chromosomes are densely staining and highly condensed, properties which makes them suitable for the production of KARYOTYPES. The spindle MICROTUBULES become attached to an area of the centromere called the kinetochore, the precise arrangement of chromosomes appearing to be random (this has important genetic implications, see INDEPENDENT ASSORTMENT) and different in mitosis and meiosis (see Fig. 220 ). The metaphase plate in the second cycle of meiosis is at right angles to the equator in metaphase I.